MNT: make print_figure kwarg wrapper support py311

Do not fully understand what changed, but without this change `walk_stack`
would start 2 frames higher (in the test module, not in backend_bases) which
would mean we never saw the frame with `print_figure` and hence was getting
warnings which we converted to failures on a vast majority of the tests.

I suspect that this is related to the fast-Python work and avoiding making
unneeded structures during the calls, but chased that theory down yet.

Discovered on a commit between py311a2 and py311a3.

Author: tacaswell

lib/matplotlib/backend_bases.py

@@ -1601,7 +1601,12 @@ def wrapper(*args, **kwargs):
             r'^savefig|print_[A-Za-z0-9]+|_no_output_draw$'
         )
         seen_print_figure = False
-        for frame, line in traceback.walk_stack(None):
+        if sys.version_info < (3, 11):
+            current_frame = None
+        else:
+            import inspect
+            current_frame = inspect.currentframe()
+        for frame, line in traceback.walk_stack(current_frame):
             if frame is None:
                 # when called in embedded context may hit frame is None.
                 break