create schedule tags based on the date time

[asieduernest12]

@serfriz this should address the issue of mutable tags resulting in issue #66

merging this pull request should allow automated builds to include a tag using the date time format described in the docs for docker/meta-actions

this extra tags serves as an in-mutable tag that will be persisted even on rebuild

possible issues

• attempting to rebuild on the same day will create multiple tag submissions due to the fact that the date time includes the seconds value in the generated tag, this could be mitigated by using the format precise to the nearest day instead of nearest second example
  type=schedule,pattern={{date 'YYYYMMDD'}}