python.kak: Do not indent after comments ending in :
python.kak: Do not indent after comments ending in :

Fixes #3693

This will not work for lines like the one below but I think that's okay
because it does work for most comments.

	foo() # foo:

Somasis/kakoune,mawww/kakoune,Somasis/kakoune,lenormf/kakoune,Somasis/kakoune,danr/kakoune,alexherbo2/kakoune,danr/kakoune,mawww/kakoune,casimir/kakoune,alexherbo2/kakoune,lenormf/kakoune,lenormf/kakoune,Somasis/kakoune,jkonecny12/kakoune,alexherbo2/kakoune,jkonecny12/kakoune,danr/kakoune,alexherbo2/kakoune,casimir/kakoune,casimir/kakoune,mawww/kakoune,casimir/kakoune,jkonecny12/kakoune,mawww/kakoune,danr/kakoune,jkonecny12/kakoune,lenormf/kakoune