Add automated testing via GitHub actions workflow

.github/workflows/test.yml

@@ -0,0 +1,31 @@
+# This workflow uses actions that are not certified by GitHub.
+# They are provided by a third-party and are governed by
+# separate terms of service, privacy policy, and support
+# documentation.
+# This workflow will download a prebuilt Ruby version, install dependencies and run tests with Rake
+# For more information see: https://github.com/marketplace/actions/setup-ruby-jruby-and-truffleruby
+
+name: Test
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby: 
+          - "2.5"
+          - "2.6"
+          - "2.7"
+          - "3.0"
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1.62.0
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - name: Install dependencies
+        run: bundle install
+      - name: Run tests
+        run: bundle exec rspec spec

.gitignore

@@ -13,3 +13,4 @@
 
 # rspec failure tracking
 .rspec_status
+.actrc

changelogs/unreleased/20210504095206366_change.yml

@@ -0,0 +1,2 @@
+"Added":
+  - GitHub action workflows for automatic testing

codelog.gemspec

@@ -23,7 +23,7 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency "thor", "~> 1.0"
 
-  spec.add_development_dependency "bundler", "~> 1.15"
+  spec.add_development_dependency "bundler", "~> 2.2"
   spec.add_development_dependency "rake", "~> 10.0"
   spec.add_development_dependency "rspec", "~> 3.4"
   spec.add_development_dependency "rubocop", "~> 0.52.1"