Drop travis.yml in favour of github actions. Move rubocop and all ci

tests into GitHub actions.

.github/workflows/ci.yml

@@ -0,0 +1,27 @@
+name: CI
+on: [push, pull_request]
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - { os: ubuntu-latest , ruby: 2.5 }
+          - { os: ubuntu-latest , ruby: 2.6 }
+          - { os: ubuntu-latest , ruby: 2.7 }
+          - { os: ubuntu-latest , ruby: 3.0 }
+          - { os: ubuntu-latest , ruby: jruby, allow-failure: true }
+          - { os: ubuntu-latest , ruby: jruby-head, allow-failure: true }
+          - { os: ubuntu-latest , ruby: head, allow-failure: true }
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+
+      - name: Run tests
+        timeout-minutes: 10
+        run: bundle exec rake

.github/workflows/isolated.yml

@@ -0,0 +1,20 @@
+name: CI isolated tests
+on: [push, pull_request]
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby: [2.7]
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+
+      - name: Run tests
+        run: bundle exec rake test_isolated

.github/workflows/rubocop.yml

@@ -0,0 +1,28 @@
+name: RuboCop
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby: [2.7]
+
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions/cache@v2
+      with:
+        path: /home/runner/bundle
+        key: bundle-use-ruby-gems-${{ hashFiles('**/Gemfile.lock') }}
+        restore-keys: bundle-use-ruby-gems-
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby }}
+    - name: Bundle install
+      run: |
+        gem install bundler -v 2.1.4
+        bundle config path /home/runner/bundle
+        bundle install
+    - name: Run linter
+      run: bundle exec rubocop --parallel

CHANGELOG.md

@@ -4,6 +4,7 @@ Get upgrade notes from Sprockets 3.x to 4.x at https://github.com/rails/sprocket
 
 ## Master
 
+- Move to GitHub actions.[#709](https://github.com/rails/sprockets/pull/709)
 - Remove remaining support for Ruby < 2.4.[#672](https://github.com/rails/sprockets/pull/672)
 
 ## 4.0.2