Drop support for PY36

Python dropped support on 2021-12-23. Our policy (#760) is to drop
support on the next point release after Python does.

* Remove py36 tests
* Test multiple recent versions of pypy
* Remove pep562 backport

.coveragerc

@@ -3,4 +3,3 @@ omit=
     *site-packages*
     tests/*
     markdown/test_tools.py
-    markdown/pep562.py

.github/workflows/tox.yml

@@ -20,10 +20,8 @@ jobs:
       fail-fast: false
       max-parallel: 4
       matrix:
-        tox-env: [py36, py37, py38, py39, py310, pypy3, pygments]
+        tox-env: [py37, py38, py39, py310, pypy37, pypy38, pypy39, pygments]
         include:
-          - tox-env: py36
-            python-version: '3.6'
           - tox-env: py37
             python-version: '3.7'
           - tox-env: py38
@@ -32,8 +30,12 @@ jobs:
             python-version: '3.9'
           - tox-env: py310
             python-version: '3.10'
-          - tox-env: pypy3
-            python-version: pypy3
+          - tox-env: pypy37
+            python-version: pypy-3.7
+          - tox-env: pypy38
+            python-version: pypy-3.8
+          - tox-env: pypy39
+            python-version: pypy-3.9
           - tox-env: pygments
             python-version: '3.7'
 
@@ -43,7 +45,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: Setup Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v3
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies

docs/change_log/release-3.4.md

@@ -2,7 +2,7 @@ title: Release Notes for v3.4
 
 # Python-Markdown 3.4 Release Notes
 
-Python-Markdown version 3.4 supports Python versions 3.6, 3.7, 3.8, 3.9, 3.10 and
+Python-Markdown version 3.4 supports Python versions 3.7, 3.8, 3.9, 3.10 and
 PyPy3.
 
 ## Backwards-incompatible changes

markdown/__init__.py

@@ -27,8 +27,6 @@
     raise ImportError('A recent version of Python 3 is required.')
 
 from .core import Markdown, markdown, markdownFromFile  # noqa: E402
-from .util import PY37                                  # noqa: E402
-from .pep562 import Pep562                              # noqa: E402
 from .__meta__ import __version__, __version_info__     # noqa: E402
 import warnings                                         # noqa: E402
 
@@ -51,11 +49,7 @@ def __getattr__(name):
         warnings.warn(
             "'{}' is deprecated. Use '{}' instead.".format(name, deprecated[0]),
             category=DeprecationWarning,
-            stacklevel=(3 if PY37 else 4)
+            stacklevel=(3 if (3, 7) <= sys.version_info else 4)
         )
         return deprecated[1]
     raise AttributeError("module '{}' has no attribute '{}'".format(__name__, name))
-
-
-if not PY37:
-    Pep562(__name__)

markdown/__meta__.py

@@ -26,7 +26,7 @@
 # (1, 2, 0, 'beta', 2) => "1.2b2"
 # (1, 2, 0, 'rc', 4) => "1.2rc4"
 # (1, 2, 0, 'final', 0) => "1.2"
-__version_info__ = (3, 3, 7, 'final', 0)
+__version_info__ = (3, 4, 0, 'dev', 0)
 
 
 def _get_version(version_info):

markdown/util.py

@@ -27,10 +27,6 @@
 from functools import wraps, lru_cache
 from itertools import count
 
-from .pep562 import Pep562
-
-PY37 = (3, 7) <= sys.version_info
-
 
 # TODO: Remove deprecated variables in a future release.
 __deprecated__ = {
@@ -462,11 +458,7 @@ def __getattr__(name):
         warnings.warn(
             "'{}' is deprecated. Use '{}' instead.".format(name, deprecated[0]),
             category=DeprecationWarning,
-            stacklevel=(3 if PY37 else 4)
+            stacklevel=(3 if (3, 7) <= sys.version_info else 4)
         )
         return deprecated[1]
     raise AttributeError("module '{}' has no attribute '{}'".format(__name__, name))
-
-
-if not PY37:
-    Pep562(__name__)

setup.py

@@ -73,7 +73,7 @@ def get_version():
     maintainer_email='python.markdown@gmail.com',
     license='BSD License',
     packages=['markdown', 'markdown.extensions'],
-    python_requires='>=3.6',
+    python_requires='>=3.7',
     install_requires=["importlib-metadata>=4.4;python_version<'3.10'"],
     extras_require={
         'testing': [
@@ -113,7 +113,6 @@ def get_version():
         'Operating System :: OS Independent',
         'Programming Language :: Python',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py36, py37, py38, py39, py310, pypy3, pygments, flake8, checkspelling, pep517check, checklinks
+envlist = py{37, 38, 39, 310}, pypy{37, 38, 39}, pygments, flake8, checkspelling, pep517check, checklinks
 isolated_build = True
 
 [testenv]
@@ -41,4 +41,3 @@ skip_install = true
 
 [flake8]
 max-line-length = 119
-exclude=markdown/pep562.py