v3.3 - Fix var name and step output commands

Some nice fixes from Fork Sync users. 🙂

PR #50

• Fix variable name to match the docs -- INPUT_TARGET_PUSH_ARGS ---> INPUT_TARGET_BRANCH_PUSH_ARGS
• Thanks @endocrimes and @kousu for calling this out

PR #48

• Fix - Output for has_new_commits was not properly set if fetching from upstream resulted in error
• Thanks @Fubuchi for the PR

PR #40

• typo fix, thanks @corneliusroemer