Create tags through GH when release PR is merged

[Sertaç Özercan]

Describe the solution you'd like
Create release tags to kick off the release of artifacts and binaries. pull_request is the event that we can use for this.

open-policy-agent/gatekeeper#3037

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• Eraser version:
• Kubernetes version: (use kubectl version):