Merge pull request #1500 from atugushev/bump-pip-to-21.1

Bump pip minimum version to `>= 21.2`

README.rst

@@ -529,5 +529,7 @@ versions as the required ``pip`` versions.
 +---------------+----------------+----------------+
 | 5.5.0         | 20.1 - 20.3.*  | 2.7, 3.5 - 3.9 |
 +---------------+----------------+----------------+
-| 6.0.0+        | 20.3+          | 3.6 - 3.9      |
+| 6.0.0 - 6.3.1 | 20.3 - 21.2.*  | 3.6 - 3.9      |
++---------------+----------------+----------------+
+| 6.4.0+        | 21.2+          | 3.6 - 3.10     |
 +---------------+----------------+----------------+

setup.cfg

@@ -33,7 +33,7 @@ install_requires =
     # direct dependencies
     click >= 7
     pep517
-    pip >= 20.3
+    pip >= 21.2
     # indirect dependencies
     setuptools  # typically needed when pip-tools invokes setup.py
     wheel  # pip plugin needed by pip-tools

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 envlist =
     # NOTE: keep this in sync with the env list in .github/workflows/ci.yml.
-    py{36,37,38,39,310,py3}-pip{20.3,previous,latest,main}-coverage
+    py{36,37,38,39,310,py3}-pip{previous,latest,main}-coverage
     checkqa
     readme
 skip_missing_interpreters = True
@@ -11,14 +11,11 @@ extras =
     testing
     coverage: coverage
 deps =
-    pipprevious: pip==20.3.*
+    pipprevious: pip==21.2.*
     piplatest: pip
     pipmain: -e git+https://github.com/pypa/pip.git@main#egg=pip
-    pip20.3: pip==20.3.*
 setenv =
     coverage: PYTEST_ADDOPTS=--strict --doctest-modules --cov --cov-report=term-missing --cov-report=xml {env:PYTEST_ADDOPTS:}
-    pipprevious,pip20.3: PIP_DISABLE_PIP_VERSION_CHECK=1
-    piplatest: PIP_USE_FEATURE=in-tree-build
 commands_pre =
     piplatest: python -m pip install -U pip
     pip --version