FIX: Map macosx to osx for ipython terminal gui toolkit

The gui toolkit is called "osx" in ipython, so we need to map
the Matplotlib's "macosx" name over to that within an ipython
session.

Author: greglucas

mpl_gui/_manage_backend.py

@@ -166,6 +166,9 @@ def show_managers(cls, *, managers, block):
         # if so are we in an IPython session
         ip = mod_ipython.get_ipython()
         if ip:
+            # macosx -> osx mapping for the osx backend in ipython
+            if required_framework == "macosx":
+                required_framework = "osx"
             ip.enable_gui(required_framework)
 
     # remember to set the global variable