Enable keymap for Python grammar only.

Fixes #10.

Author: dpo

keymaps/python-debugger.cson

@@ -7,6 +7,6 @@
 
 # For more detailed documentation see
 # https://atom.io/docs/latest/behind-atom-keymaps-in-depth
-"atom-workspace":
+"atom-text-editor[data-grammar='source python']":
   "alt-r": "python-debugger:toggle"
   "alt-shift-r": "python-debugger:breakpoint"