add release workflow for publishing to RubyGems

Author: topherbullock

.github/workflows/ci.yml

@@ -17,8 +17,6 @@ jobs:
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.entry.ruby }}
-          bundler-cache: false
-      - name: Bundle install
-        run: bundle install
+          bundler-cache: true
       - run: bundle exec rake test
         continue-on-error: ${{ matrix.entry.allowed-failure }}