Allow releaser target ref and SHA inputs

[galargh]

Summary

• Add optional ref and sha inputs to the reusable releaser workflow.
• Check out the requested SHA while using the supplied ref for release-branch and release-PR policy checks.
• Add the 1.0.45 changelog entry for the releaser workflow enhancement.

Validation

• YAML parse and git diff --check passed before pushing.

[github-actions]

v1.0.45

Added

• allow the releaser workflow to release a specific SHA while evaluating release policy against a separate ref