Also remove default `--with-label` value and add `--without-approval`
option.
Reviews could be automatically dismissed on new commits pushed (there is
an option for that in repository settings on Github). That is not the
case for labels. They remain attached to a PR, even when new commits are
pushed. This is undesirable and creates security concerns, because
someone could introduce untested code just before the automerge happens.
Co-authored-by: Eric Knibbe <enk3@outlook.com>
