maintenance: focus on Python 3.8+ (#153)

* maintenance: focus on modern Python versions

* fix errors

.github/workflows/tests.yml

@@ -21,10 +21,6 @@ jobs:
         env: [{ MINIMAL: "true" }, { MINIMAL: "false" }]
         include:
         # custom python versions
-        - os: ubuntu-20.04
-          python-version: 3.6
-        - os: ubuntu-latest
-          python-version: 3.7
         - os: macos-latest
           python-version: 3.8
         - os: macos-latest

htmldate/__init__.py

@@ -14,14 +14,6 @@
 
 from datetime import datetime
 
-try:
-    datetime.fromisoformat  # type: ignore[attr-defined]
-# Python 3.6
-except AttributeError:  # pragma: no cover
-    from backports.datetime_fromisoformat import MonkeyPatch  # type: ignore
-
-    MonkeyPatch.patch_fromisoformat()
-
 from .core import find_date
 
 logging.getLogger(__name__).addHandler(logging.NullHandler())

htmldate/validators.py

@@ -64,8 +64,7 @@ def is_valid_format(outputformat: str) -> bool:
     dateobject = datetime(2017, 9, 1, 0, 0)
     try:
         dateobject.strftime(outputformat)
-    # other than ValueError: Python < 3.7 only
-    except (NameError, TypeError, ValueError) as err:
+    except (TypeError, ValueError) as err:
         LOGGER.error("wrong output format or type: %s %s", outputformat, err)
         return False
     # test in abstracto (could be the only test)

setup.py

@@ -80,8 +80,6 @@ def get_version(package):
         "Operating System :: POSIX :: Linux",
         "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",
         "Programming Language :: Python :: 3.10",
@@ -113,18 +111,15 @@ def get_version(package):
     license="Apache-2.0",
     packages=["htmldate"],
     include_package_data=True,
-    python_requires=">=3.6",
+    python_requires=">=3.8",
     install_requires=[
-        "backports-datetime-fromisoformat; python_version < '3.7'",
-        "charset_normalizer >= 3.0.1; python_version < '3.7'",
-        "charset_normalizer >= 3.3.2; python_version >= '3.7'",
+        "charset_normalizer >= 3.3.2",
         "dateparser >= 1.1.2",  # 1.1.3+ slower
         # see tests on Github Actions
         "lxml == 4.9.2 ; platform_system == 'Darwin' and python_version <= '3.8'",
         "lxml >= 5.2.2, < 6 ; platform_system != 'Darwin' or python_version > '3.8'",
         "python-dateutil >= 2.8.2",
-        "urllib3 >= 1.26, < 2; python_version < '3.7'",
-        "urllib3 >= 1.26, < 3; python_version >= '3.7'",
+        "urllib3 >= 1.26, < 3",
     ],
     extras_require=extras,
     entry_points={