Add CI to run specs

Adds GitHub Actions CI to run the ruby gem specs.

Also removes a bunch of outdated files.

Author: Brett Mortensen

.github/workflows/test.yml

@@ -0,0 +1,20 @@
+name: Test
+
+on: [push]
+
+jobs:
+  Test:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        bundler-cache: true
+        ruby-version: 2.6
+    - name: Install dependencies
+      run: bundle install
+    - name: Check openapi.yml
+      run: bundle exec rake