restore rdflib.query.Processor to its previous state

`rdflib.query.Processor` is an interface for plugins, and changes to it
that broaden it will affect existing plugins that only support the
narrower interface.

rdflib/query.py

@@ -57,8 +57,8 @@ def __init__(self, graph: "Graph"):
     def query(  # type: ignore[empty-body]
         self,
         strOrQuery: Union[str, "Query"],  # noqa: N803
-        initBindings: Optional[Mapping["str", "Identifier"]] = {},  # noqa: N803
-        initNs: Optional[Mapping[str, Any]] = {},  # noqa: N803
+        initBindings: Mapping["str", "Identifier"] = {},  # noqa: N803
+        initNs: Mapping[str, Any] = {},  # noqa: N803
         DEBUG: bool = False,
     ) -> Mapping[str, Any]:
         pass