Remove manual kwargs-only check in call

Fix #350.

Author: bluetech

src/pluggy/_hooks.py

@@ -381,9 +381,7 @@ def _verify_all_args_are_provided(self, kwargs: Mapping[str, object]) -> None:
                     )
                     break
 
-    def __call__(self, *args: object, **kwargs: object) -> Any:
-        if args:
-            raise TypeError("hook calling supports only keyword arguments")
+    def __call__(self, **kwargs: object) -> Any:
         assert (
             not self.is_historic()
         ), "Cannot directly call a historic hook - use call_historic instead."

testing/test_invocations.py

@@ -33,10 +33,10 @@ def hello(self, arg):
 
     pm.add_hookspecs(Api)
     with pytest.raises(TypeError) as exc:
-        pm.hook.hello(3)
+        pm.hook.hello(3)  # type: ignore[call-arg]
 
-    comprehensible = "hook calling supports only keyword arguments"
-    assert comprehensible in str(exc.value)
+    message = "__call__() takes 1 positional argument but 2 were given"
+    assert message in str(exc.value)
 
 
 def test_opt_in_args(pm: PluginManager) -> None: