Deprecate some untested, never used axes_grid1 methods.

They've never been used in the entire git history, are untested, and
seem easy enough to reimplement using public API if someone *really*
needs them.

Author: anntzer

doc/api/next_api_changes/deprecations/20063-AL.rst

@@ -0,0 +1,4 @@
+``Divider.get_vsize_hsize`` and ``Grid.get_vsize_hsize``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+These ``axes_grid1`` methods are deprecated.  Copy their implementations if
+needed.

lib/mpl_toolkits/axes_grid1/axes_divider.py

@@ -58,6 +58,7 @@ def get_horizontal_sizes(self, renderer):
     def get_vertical_sizes(self, renderer):
         return [s.get_size(renderer) for s in self.get_vertical()]
 
+    @_api.deprecated("3.5")
     def get_vsize_hsize(self):
         vsize = Size.AddList(self.get_vertical())
         hsize = Size.AddList(self.get_horizontal())

lib/mpl_toolkits/axes_grid1/axes_grid.py

@@ -326,6 +326,7 @@ def set_axes_locator(self, locator):
     def get_axes_locator(self):
         return self._divider.get_locator()
 
+    @_api.deprecated("3.5")
     def get_vsize_hsize(self):
         return self._divider.get_vsize_hsize()