Invalidate wxGrid best size when its associated table changes.

The number of grid cells changes too, so the old best size can't be used any
more.

Closes #14761.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73243 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/grid.cpp

@@ -2414,6 +2414,8 @@ wxGrid::SetTable(wxGridTableBase *table,
         m_created = true;
     }
 
+    InvalidateBestSize();
+
     return m_created;
 }