Support to merge the SONiC package versions upgrade pull request automatically.
#### How I did it
Add the automerge tag in the pull request.
1. Sent by the author mssonicbld
2. Only contains changes in files/build/**/*
3. Only for the specified branch 202012
Merge the pull request.
1. Sent by the author mssonicbld
2. The Azure Pipelines checker complete and successful
3. The pull request contains label automerge
