Fix return type of get_plot_commands

The typing PR found that this was returning a generator [1], but this
was an error from matplotlib#24000, as 3.6 and earlier returned a list.

[1] matplotlib#24976 (comment)

Author: QuLogic

lib/matplotlib/pyplot.py

@@ -2066,8 +2066,8 @@ def get_plot_commands():
     NON_PLOT_COMMANDS = {
         'connect', 'disconnect', 'get_current_fig_manager', 'ginput',
         'new_figure_manager', 'waitforbuttonpress'}
-    return (name for name in _get_pyplot_commands()
-            if name not in NON_PLOT_COMMANDS)
+    return [name for name in _get_pyplot_commands()
+            if name not in NON_PLOT_COMMANDS]
 
 
 def _get_pyplot_commands():