Unlock requirements are overly strict

[mwarkentin]

People other than the original author should be able to unlock PRs / slices. Currently this requires going outside of TACOS and using the CLI to do a terraform force-unlock.

With our distributed company, this can block someone for hours to a day depending on who has a lock.

tf-lock-release: failure: not jredmond-sentry@10396.ops.getsentry.github.invalid: .(mwarkentin@10396.ops.getsentry.github.invalid)

Alternative, keep the existing functionality but have a force-unlock option to bypass this check.