Remove Python version check (#167)

* Adjust Python version check.

* Remove Python version check.

changelogs/fragments/167-python.yml

@@ -0,0 +1,6 @@
+bugfixes:
+  - "Remove Python version check that was checking for Python >= 3.6 (instead of >= 3.9).
+     This check is not really necessary since ``pyproject.toml`` declares ``requires-python``,
+     and old enough Python versions where pip does not know about ``requires-python``
+     will not load antsibull-changelog due to syntax errors anyway
+     (https://github.com/ansible-community/antsibull-changelog/pull/167)."

src/antsibull_changelog/cli.py

@@ -869,8 +869,4 @@ def main() -> int:
     See constants.py for the return codes.
     """
 
-    if sys.version_info < (3, 6):
-        print("Needs Python 3.6 or later")
-        return C.RC_OLD_PYTHON
-
     return run(sys.argv)

src/antsibull_changelog/constants.py

@@ -12,5 +12,4 @@
 RC_UNHANDLED_ERROR = 1  # Unhandled error.  See the Traceback for more information.
 RC_BAD_CLI_ARG = 2  # There was a problem with the command line arguments.
 RC_INVALID_FRAGMENT = 3  # Found invalid changelog fragments.
-RC_OLD_PYTHON = 4  # Needs to be run on a newer version of Python.
 RC_COMMAND_FAILED = 5  # Problem occurred which prevented the execution of the command.