[cleanup] cleanup scripts/catall.py
[cleanup] cleanup scripts/catall.py

- use str.format(...) instead of modulo for type specifier
  arguments.
- use single quotes for string literals
- remove preleading "u" fron strings

Change-Id: Ib56945ca33bfb616b5e0905314455755f96d3a46

wikimedia/pywikibot-core,wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core