Remove deprecated get_visit_fn method

Replicates graphql/graphql-js@f9d79f1

Author: Cito

src/graphql/language/visitor.py

@@ -146,17 +146,6 @@ def get_enter_leave_for_kind(self, kind: str) -> EnterLeaveVisitor:
             self.enter_leave_map[kind] = enter_leave
             return enter_leave
 
-    def get_visit_fn(
-        self, kind: str, is_leaving: bool = False
-    ) -> Optional[Callable[..., Optional[VisitorAction]]]:
-        """Get the visit function for the given node kind and direction.
-
-        .. deprecated:: 3.2
-           Please use ``get_enter_leave_for_kind`` instead. Will be removed in v3.3.
-        """
-        enter_leave = self.get_enter_leave_for_kind(kind)
-        return enter_leave.leave if is_leaving else enter_leave.enter
-
 
 class Stack(NamedTuple):
     """A stack for the visit function."""

tests/language/test_visitor.py

@@ -242,12 +242,6 @@ def leave_document(*args):
             visitor.leave,
         )
 
-        # also test deprecated method
-        assert visitor.get_visit_fn("document") == visitor.enter_document
-        assert visitor.get_visit_fn("field") == visitor.enter
-        assert visitor.get_visit_fn("document", True) == visitor.leave_document
-        assert visitor.get_visit_fn("field", True) == visitor.leave
-
     def validates_path_argument():
         ast = parse("{ a }", no_location=True)
         visited = []