feat: compute annotations only if necessary

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

Author: felixscherz

Lib/typing.py

@@ -2020,11 +2020,12 @@ def _proto_hook(cls, other):
                 break
 
             # ...or in annotations, if it is a sub-protocol.
-            annotations = _lazy_annotationlib.get_annotations(base, format=_lazy_annotationlib.Format.FORWARDREF)
             if (
                 issubclass(other, Generic)
                 and getattr(other, "_is_protocol", False)
-                and attr in annotations
+                and attr in _lazy_annotationlib.get_annotations(
+                    base, format=_lazy_annotationlib.Format.FORWARDREF
+                )
             ):
                 break
         else: