Provide a GitHub workflow for creating/updating major tags when releasing this action

This will allow downstream users to reference the gitlance version by its major number, which is the expectation as per the current `README.md` documentation.

Start with README.md to confirm how downstream users are expected to reference major versions, then inspect the repository's release setup and GitHub Actions documentation. Done means a workflow creates or updates the major tag when this action is released and matches the versioning expectation documented in README.md.

Written by the indexing model from the issue text.