managers, meta: migrate off of pkg_resources to importlib_metadata

This fixes installing `sopel` (which depends on this package) from
scratch on a new environment that does not ship with `pkg_resources` as
part of the Python stdlib (py3.12+) and also omits `setuptools` (some
distros, fresh venvs, probably others).

Includes slight cleanup of comments, log messages, and imports, but I
think not enough to be worth a separate commit or pull request.

pyproject.toml

@@ -41,7 +41,9 @@ classifiers = [
 requires-python = ">=3.8"
 dependencies = [
     "sopel>=7.1",
+    # sopel also requires both of the below, but it's best to be explicit
     "requests",
+    "importlib_metadata>=3.6",
 ]
 
 [project.urls]

sopel_help/managers.py

@@ -1,6 +1,10 @@
 """Sopel Help Managers."""
 
-import pkg_resources
+# 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
 
 PROVIDERS_ENTRY_POINT = 'sopel_help.providers'
 
@@ -18,8 +22,8 @@ def provider(self):
     def provider_names(self):
         """Names of the available providers."""
         if self._provider_list is None:
-            entry_points = pkg_resources.iter_entry_points(
-                PROVIDERS_ENTRY_POINT)
+            entry_points = importlib_metadata.entry_points(
+                group=PROVIDERS_ENTRY_POINT)
             self._provider_list = [
                 entry_point.name
                 for entry_point in entry_points
@@ -37,16 +41,18 @@ def load_provider(self, name):
         :return: a provider instance
         :rtype: :class:`sopel_help.providers.AbstractProvider`
 
-        The provider will be loaded from an entry point and then instanciated
+        The provider will be loaded from an entry point and then instantiated
         to be returned as is (no setup, no configure).
         """
-        entry_points = pkg_resources.iter_entry_points(
-            PROVIDERS_ENTRY_POINT, name)
+        # 1. get EntryPoints matching the group and name
+        entry_points = importlib_metadata.entry_points(
+            group=PROVIDERS_ENTRY_POINT, name=name)
 
+        # 2. get just the EntryPoint matching `name`
         try:
-            entry_point = next(entry_points)
-        except StopIteration as err:
-            raise RuntimeError('Cannot found help provider %s' % name) from err
+            entry_point = entry_points[name]
+        except KeyError:
+            raise RuntimeError('Cannot find help provider %r' % name) from None
 
         # 3. load the entry point
         provider_maker = entry_point.load()

sopel_help/providers.py

@@ -5,6 +5,7 @@
 import urllib
 
 import requests
+
 from sopel.tools import get_logger
 
 from sopel_help import mixins