Remove a deprecated method from importlib_metadata (#991)

* Remove a deprecated method

The dict interface from "importlib_metadata" is deprecated, so it must not be used as well.

* Upgrade the minimal `importlib_metadata` to 3.9.1

That way, the deprecated feature removed won't be harmful.

* Update pyface/base_toolkit.py

Convert a positional argument from "importlib_metadata.entry_points().select()" into a keyword argument.

Co-authored-by: Poruri Sai Rahul <rahul.poruri@gmail.com>

* Update pyface/base_toolkit.py

Convert a positional argument from "importlib_metadata.entry_points().select()" into a keyword argument.

Co-authored-by: Poruri Sai Rahul <rahul.poruri@gmail.com>

* Min required version is 3.6.0, not 3.9.0

the select interface was introduced in 3.6.0.
ref https://importlib-metadata.readthedocs.io/en/latest/history.html#v3-6-0

* The external package is now needed for python < 3.10

this is because the select interface isn't available in
any of the prior python versions

Co-authored-by: Poruri Sai Rahul <rahul.poruri@gmail.com>

pyface/__init__.py

@@ -19,7 +19,7 @@
 
 
 __requires__ = [
-    'importlib-metadata; python_version<"3.8"',
+    'importlib-metadata>=3.6.0; python_version<"3.10"',
     'importlib-resources>=1.1.0; python_version<"3.9"',
     "traits>=6.2"
 ]

pyface/base_toolkit.py

@@ -187,7 +187,7 @@ def import_toolkit(toolkit_name, entry_point="pyface.toolkits"):
         If no toolkit is found, or if the toolkit cannot be loaded for some
         reason.
     """
-    entry_point_group = importlib_metadata.entry_points()[entry_point]
+    entry_point_group = importlib_metadata.entry_points().select(group=entry_point)
     plugins = [
         plugin for plugin in entry_point_group if plugin.name == toolkit_name
     ]
@@ -256,7 +256,7 @@ def find_toolkit(entry_point, toolkits=None, priorities=default_priorities):
         return import_toolkit(ETSConfig.toolkit, entry_point)
 
     entry_points = [
-        plugin for plugin in importlib_metadata.entry_points()[entry_point]
+        plugin for plugin in importlib_metadata.entry_points().select(group=entry_point)
         if toolkits is None or plugin.name in toolkits
     ]
     for plugin in sorted(entry_points, key=priorities):