Bump version to v4.3.1

Bump version to v4.3

Bump version to v4.2.1

bump version to v4.2.0

bump version to 4.1.2

bump to 4.1.1

Bumping version to v4.1 [ci skip]

bump version to 4.0.3

bump version to 4.0.1

Merge pull request python-telegram-bot#213 from python-telegram-bot/p…

…rep34

Prepare Release of v3.4