deps: forget about python_version specifier for importlib_metadata

My clean install of Python 3.10 on Ubuntu 20.04 (via deadsnakes/ppa)
came with an old version of `importlib_metadata` that tripped up the
fallback logic I so carefully included.

Rather than contort the import logic, let's just use the backport until
Sopel no longer supports Python versions where stdlib can't replace it.

requirements.txt

@@ -5,5 +5,5 @@ geoip2>=4.0,<5.0
 requests>=2.24.0,<3.0.0
 dnspython<3.0
 sqlalchemy>=1.4,<1.5
-importlib_metadata>=3.6; python_version < '3.10'
+importlib_metadata>=3.6
 packaging

sopel/__init__.py

@@ -16,11 +16,9 @@
 import re
 import sys
 
-try:
-    import importlib.metadata as importlib_metadata
-except ImportError:
-    # TODO: remove fallback when dropping py3.7
-    import importlib_metadata
+# TODO: replace with stdlib importlib.metadata when dropping py3.7
+# version info used in this module works from py3.8+
+import importlib_metadata
 
 __all__ = [
     'bot',

sopel/plugins/__init__.py

@@ -33,12 +33,11 @@
 import itertools
 import os
 
-try:
-    import importlib_metadata
-except ImportError:
-    # TODO: use stdlib only when possible, after dropping py3.9
-    # stdlib does not support `entry_points(group='filter')` until py3.10
-    import importlib.metadata as importlib_metadata
+# TODO: use stdlib importlib.metadata when possible, after dropping py3.9.
+# Stdlib does not support `entry_points(group='filter')` until py3.10, but
+# fallback logic is more trouble than it's worth when e.g. clean Ubuntu
+# py3.10 envs include old versions of this backport.
+import importlib_metadata
 
 from . import exceptions, handlers, rules  # noqa
 

sopel/plugins/handlers.py

@@ -559,8 +559,10 @@ class EntryPointPlugin(PyModulePlugin):
         Entry points are a `standard packaging mechanism`__ for Python, used by
         other applications (such as ``pytest``) for their plugins.
 
-        The ``importlib_metadata`` backport package is used on Python versions
-        older than 3.10, but its API is the same as :mod:`importlib.metadata`.
+        The ``importlib_metadata`` backport package is used for consistency
+        across all of Sopel's supported Python versions. Its API matches that
+        of :mod:`importlib.metadata` from Python 3.10 and up; Sopel will drop
+        this external requirement when practical.
 
         .. __: https://packaging.python.org/en/latest/specifications/entry-points/
 

test/plugins/test_plugins_handlers.py

@@ -4,14 +4,10 @@
 import os
 import sys
 
+# TODO: use stdlib importlib.metadata when dropping py3.9
+import importlib_metadata
 import pytest
 
-try:
-    import importlib.metadata as importlib_metadata
-except ImportError:
-    # TODO: remove fallback when dropping py3.9
-    import importlib_metadata
-
 from sopel.plugins import handlers
 
 

test/test_plugins.py

@@ -3,14 +3,10 @@
 
 import sys
 
+# TODO: switch to stdlib importlib.metdata when dropping py3.9
+import importlib_metadata
 import pytest
 
-try:
-    import importlib.metadata as importlib_metadata
-except ImportError:
-    # TODO: remove fallback when dropping py3.9
-    import importlib_metadata
-
 from sopel import plugins