Add alias for GIMP 2.10

GIMP 2.10 uses `gimp` as the classname
rather than `gimp-2.8` which was used for GIMP 2.8

Author: woofers

autoname_workspaces.py

@@ -67,6 +67,7 @@
     'filezilla': fa.icons['server'],
     'firefox': fa.icons['firefox'],
     'firefox-esr': fa.icons['firefox'],
+    'gimp': fa.icons['image'],
     'gimp-2.8': fa.icons['image'],
     'gnome-control-center': fa.icons['toggle-on'],
     'gnome-terminal-server': fa.icons['terminal'],