[python mode] Add f to delimiter stripping for Python mode

So f-strings get terminated correctly

mode/python/python.js

@@ -185,7 +185,7 @@
     }
 
     function tokenStringFactory(delimiter) {
-      while ("rub".indexOf(delimiter.charAt(0).toLowerCase()) >= 0)
+      while ("rubf".indexOf(delimiter.charAt(0).toLowerCase()) >= 0)
         delimiter = delimiter.substr(1);
 
       var singleline = delimiter.length == 1;