chore: add GitHub action to publish the gem to RubyGems

It runs on any git tag push with name starting with 'v'
(so any tag like v1.10.0 will trigger)

Author: wpramio

.github/publish-gem-on-tag-push.yml

@@ -0,0 +1,16 @@
+on:
+  push:
+    branches:
+      - master
+    tags:
+      - v*
+
+---
+
+- name: Publish gem on tag push
+  uses: dawidd6/action-publish-gem@v1.2.0
+  with:
+    # Optional, will publish to RubyGems if specified
+    api_key: ${{secrets.RUBYGEMS_API_KEY}}
+    # Optional, will publish to GitHub Packages if specified
+    github_token: ${{secrets.GITHUB_TOKEN}}