Remove fixme note

Per T74941#794299, MediaWiki does it since 1.11 while Pywikibot now
supports 1.14 or higher.

Change-Id: I1e941d6b760a32919465c4d01bbd3e0f3143629c

pywikibot/cosmetic_changes.py

@@ -619,8 +619,6 @@ def removeNonBreakingSpaceBeforePercent(self, text):
         Newer MediaWiki versions automatically place a non-breaking space in
         front of a percent sign, so it is no longer required to place it
         manually.
-
-        FIXME: which version should this be run on?
         """
         text = textlib.replaceExcept(text, r'(\d) %', r'\1 %',
                                      ['timeline'])