Create test workflow

.github/workflows/ruby.yml

@@ -0,0 +1,37 @@
+# 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: Ruby
+
+on:
+  push:
+    branches: ["master"]
+  pull_request:
+    branches: ["master"]
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby-version: ["2.6", "2.7", "3.0"]
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Ruby
+        # To automatically get bug fixes and new Ruby versions for ruby/setup-ruby,
+        # change this to (see https://github.com/ruby/setup-ruby#versioning):
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby-version }}
+          bundler: 1.17.3
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+      - name: Run tests
+        run: bundle exec rake test

video_thumb.gemspec

@@ -20,7 +20,7 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency "json", "~> 2.1"
   spec.add_runtime_dependency "nokogiri", "~> 1.8"
-  spec.add_development_dependency "bundler", "~> 1.7"
-  spec.add_development_dependency "rake", "~> 10.0"
-  spec.add_development_dependency "minitest", "~> 5.8"
+  spec.add_development_dependency "bundler"
+  spec.add_development_dependency "rake"
+  spec.add_development_dependency "minitest"
 end