adding rspec workflow

.github/workflows/rspec.yml

@@ -0,0 +1,45 @@
+name: RSpec
+on: [push, pull_request]
+
+jobs:
+  rspec:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest]
+        ruby: [2.7]
+    runs-on: ${{ matrix.os }}
+    services:
+      redis:
+        image: redis
+        ports:
+          - 6379:6379
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - name: RSpec run
+        run: |
+          bash -c "
+            bundle exec rspec
+            [[ $? -ne 2 ]]
+          "
+  rspec-all:
+    needs: rspec
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ ubuntu-latest ]
+        ruby: [2.5, 2.6, '3.0', head, truffleruby]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - run: bundle exec rspec
+