Use --force-with-lease instead of --force for updating remote branches after rebases

[`--force-with-lease`](https://git-scm.com/docs/git-push#git-push---no-force-with-lease) is safer than `--force` because it checks that no one else has pushed to the branch. Using this flag is recommended by [k88hudson/git-flight-rules](https://github.com/k88hudson/git-flight-rules#i-tried-to-push-my-amended-commit-to-a-remote-but-i-got-an-error-message).