mrhlpr finish tries to self-approve MRs

When using $ mrhlpr finish to merge one's own MR, mrhlpr will try to approve the MR despite that it's your own MR. I'm not sure how this best could be resolved, maybe the GitLab API could be used to check which GitLab user owns the authentication token and avoid approving if it matches the MR's author?

@pabloyoyoista