Add Release Workflow

[OutlawAndy]

Why?

1. Facilitate version changes outside of PRs in order to avoid the merge conflicts caused by every PR necessarily making conflicting changes to the same handful of files.
2. Facilitate Github releases and Gem pushes in response to version changes.

[Copilot]

Pull request overview

Adds GitHub Actions workflows to automate version bumping, GitHub Release creation, and RubyGems publishing for the rolemodel-rails gem.

Changes:

• Introduces a tag-driven release workflow intended to create a GitHub Release and publish the gem to RubyGems.
• Adds a manually-triggered version bump workflow that commits version changes.
• Updates CI runner and removes gem build from bin/bump_version.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
bin/bump_version	Removes local gem build step from the version bump script.
.github/workflows/release.yml	Adds tag-triggered workflow to create a GitHub Release and publish to RubyGems.
.github/workflows/ci.yml	Switches CI runner to ubuntu-latest.
.github/workflows/bump_version.yml	Adds workflow_dispatch job to bump/commit (intended to tag/release).
.github/pull_request_template.md	Updates contributor guidance around version management.