Support for importlib-metadata EntryPoint.matches()

I was trying to follow up on #562 using PyOxidizer 0.22.0, updated the dependencies to keyring==23.7.0 and importlib-metadata==4.12.0, and got the following (after adjusting mercurial_keyring to print a stacktrace when the keyring module raises an exception):

keyring: keyring backend doesn't seem to work, password can not be restored. Falling back to prompts. Error details: 'EntryPoint' object has no attribute 'matches'
Traceback (most recent call last):
  File "C:/Users/Matt/projects/foss/mercurial/mercurial_keyring/mercurial_keyring.py", line 235, in _read_password_from_keyring
    password = keyring.get_password(KEYRING_SERVICE, pwdkey)
  File "keyring.core", line 55, in get_password
    return get_keyring().get_password(service_name, username)
  File "keyring.core", line 32, in get_keyring
    init_backend()
  File "keyring.core", line 83, in init_backend
    set_keyring(_detect_backend(limit))
  File "keyring.core", line 101, in _detect_backend
    filter(limit, backend.get_all_keyring()),
  File "keyring.util", line 22, in wrapper
    func.always_returns = func(*args, **kwargs)
  File "keyring.backend", line 212, in get_all_keyring
    _load_plugins()
  File "keyring.backend", line 196, in _load_plugins
    for ep in metadata.entry_points(group='keyring.backends'):
  File "importlib_metadata", line 1047, in entry_points
    return SelectableGroups.load(eps).select(**params)
  File "importlib_metadata", line 505, in select
    return self._all.select(**params)
  File "importlib_metadata", line 381, in select
    return EntryPoints(ep for ep in self if ep.matches(**params))
  File "importlib_metadata", line 381, in <genexpr>
    return EntryPoints(ep for ep in self if ep.matches(**params))
AttributeError: 'EntryPoint' object has no attribute 'matches'

Reproduce the failure with PyOxidizer 0.22.0, keyring 23.7.0, and importlib-metadata 4.12.0. Start at keyring.backend._load_plugins and metadata.entry_points(group='keyring.backends'), then trace the EntryPoint.matches() call. Done means backend discovery no longer raises AttributeError with these dependencies.