Update tox configuration to use tox >= 4.4.0

Tox 4.0.0 was released in December 2022 [1] and was a major rewrite of
the internals of the package that included numerous backwards
incompatible changes [2]. Along with that major rewrite was a long
period of instability in the package with a flurry of 47 releases [3]
since 4.0.0 (which has only been 3-4 months). At the time of the 4.0.0
release we pinned the tox version in CI with Qiskit#761 to avoid this
instability as our tox configuration was not compatible with tox 4.x.y
and tox was actually not compatible with how we had things configured
more generally. The hope was that tox would stabilize more, fix the
issues that plagued the tox 4 release series and we'd be able to relax
that pin without requiring bumping our minimum tox version to ensure
users could use either the old version or the new version locally.
However, since Qiskit#761 that hope hasn't been realized the divergence
between tox 3 and tox 4 has only widened and at least personally I'm not
convinced of an improvement in stability to the tox 4 release series.
That being said however, this is becoming a developer pain as by default
when setting up a new build environment pip will install the latest
version of tox and we don't have an effective mechanism to pin the tox
version for users as you need to install tox manually as it's the
primary python development entrypoint we use. The only only avenue to
address this would be documentation updates in the CONTRIBUTING.md file,
which we didn't update at the time in Qiskit#761 because it was meant to be
a version temporary pin that has turned out to not be so temporary.

Since it's been >3 months since we first pinned the tox version and that
pin was meant to be temporary this commit removes that pin and bumps our
minimum supported tox version to be 4.4.0, which despite not being
compatible with tox < 4 as we originally hoped, at least seems to work
fine with install rustworkx after updating the configuration file. This
should hopefully ease the onboarding experience for developers when
working with rustworkx and trying to bootstrap a local development
environment. Longer term I expect we'll look at moving off of tox,
as it no longer seems like a project we can rely on (especially as
a key component for our development and CI infrastructure) for rustworkx
and instead look at something like `nox` which I've heard good things
about and know that PyO3 had moved to it a year or two ago.

Fixes Qiskit#812

[1] https://pypi.org/project/tox/4.0.0/
[2] https://tox.wiki/en/latest/upgrading.html
[3] https://pypi.org/project/tox/#history

.github/workflows/docs_dev.yml

@@ -17,7 +17,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -U virtualenv setuptools wheel 'tox<4'
+        pip install -U virtualenv setuptools wheel tox
         sudo apt-get install graphviz pandoc
     - name: Build and publish
       env:

.github/workflows/docs_release.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -U virtualenv setuptools wheel 'tox<4'
+        pip install -U virtualenv setuptools wheel tox
         sudo apt-get install graphviz pandoc
     - name: Build and publish
       env:

.github/workflows/main.yml

@@ -80,7 +80,7 @@ jobs:
           toolchain: ${{ matrix.rust }}
           targets: ${{ matrix.platform.rust-target }}
       - name: 'Install dependencies'
-        run: python -m pip install --upgrade 'tox<4'
+        run: python -m pip install --upgrade tox
       - name: 'Install binary dependencies'
         run: sudo apt-get install -y graphviz
         if: runner.os == 'Linux'
@@ -103,7 +103,7 @@ jobs:
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
       - name: 'Install dependencies'
-        run: python -m pip install --upgrade 'tox<4'
+        run: python -m pip install --upgrade tox
       - name: 'Run rustworkx stub tests'
         run: tox -estubs
   tests_retworkx_compat:
@@ -132,7 +132,7 @@ jobs:
           toolchain: ${{ matrix.rust }}
           targets: ${{ matrix.platform.rust-target }}
       - name: 'Install dependencies'
-        run: python -m pip install --upgrade 'tox<4'
+        run: python -m pip install --upgrade tox
       - name: 'Install binary dependencies'
         run: sudo apt-get install -y graphviz
         if: runner.os == 'Linux'
@@ -202,7 +202,7 @@ jobs:
       - name: Install binary deps
         run: sudo apt-get install -y graphviz
       - name: Install deps
-        run: pip install -U 'tox<4'
+        run: pip install -U tox
       - name: Build Docs
         run: tox -edocs
       - uses: actions/upload-artifact@v3

tox.ini

@@ -1,10 +1,10 @@
 [tox]
-minversion = 2.1
+minversion = 4.4.0
 envlist = py37, py38, py39, py310, py311, lint
 isolated_build = true
 
 [testenv]
-install_command = pip install -c{toxinidir}/constraints.txt -U {opts} {packages}
+install_command = python -I -m pip install -c{toxinidir}/constraints.txt -U {opts} {packages}
 setenv =
   VIRTUAL_ENV={envdir}
   LANGUAGE=en_US
@@ -19,14 +19,15 @@ deps =
 extras =
   mpl
   graphviz
-passenv = RETWORKX_TEST_PRESERVE_IMAGES RUSTWORKX_PKG_NAME
+passenv =
+  RETWORKX_TEST_PRESERVE_IMAGES
+  RUSTWORKX_PKG_NAME
 changedir = {toxinidir}/tests
 commands =
   stestr run {posargs}
 
 [testenv:lint]
 basepython = python3
-envdir = .tox/lint
 deps =
   black~=22.0
   flake8
@@ -44,7 +45,10 @@ setenv =
   {[testenv]setenv}
 deps =
   -r {toxinidir}/docs/source/requirements.txt
-passenv = {[testenv]passenv} RETWORKX_DEV_DOCS RETWORKX_LEGACY_DOCS
+passenv =
+  {[testenv]passenv}
+  RETWORKX_DEV_DOCS
+  RETWORKX_LEGACY_DOCS
 changedir = {toxinidir}/docs
 commands =
   python -m ipykernel install --user
@@ -53,14 +57,12 @@ commands =
 
 [testenv:black]
 basepython = python3
-envdir = .tox/lint
 deps =
   black~=22.0
 commands = black {posargs} '../rustworkx' '../tests' '../retworkx'
 
 [testenv:stubs]
 basepython = python3
-envdir = .tox/stubs
 deps =
   mypy==1.0.1
 commands = python -m mypy.stubtest --concise --ignore-missing-stub rustworkx.rustworkx