DEV: Replace Travis with GitHub Actions (#202)

.github/workflows/ci.yml

@@ -0,0 +1,54 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+    tags:
+      - v*
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        ruby:
+          - 2.5
+          - 2.6
+          - 2.7
+
+    steps:
+      - uses: actions/checkout@v1
+
+      - name: Setup ruby
+        uses: actions/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          architecture: 'x64'
+
+      - name: Setup bundler
+        run: gem install bundler
+
+      - name: Setup gems
+        run: bundle install
+
+      - name: Rubocop
+        run: bundle exec rubocop
+
+      - name: RSpec
+        run: bundle exec rspec
+
+  publish:
+    if: contains(github.ref, 'refs/tags/v')
+    needs: build
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Release Gem
+        uses: CvX/publish-rubygems-action@master
+        env:
+          RUBYGEMS_API_KEY: ${{secrets.RUBYGEMS_API_KEY}}