import re
rx = r'\d+(?=:$)'
s="""firefox-x 46.0:
google 5.1.0.1:
- request
- branch"""
print(re.sub(rx, lambda x: str(int(x.group(0)) + 1), s, 1, re.M))
aW1wb3J0IHJlCnJ4ID0gcidcZCsoPz06JCknCnM9IiIiZmlyZWZveC14IDQ2LjA6Cmdvb2dsZSA1LjEuMC4xOgogICAgLSByZXF1ZXN0CiAgICAtIGJyYW5jaCIiIgogICAgCnByaW50KHJlLnN1YihyeCwgbGFtYmRhIHg6IHN0cihpbnQoeC5ncm91cCgwKSkgKyAxKSwgcywgMSwgcmUuTSkp