DEV: Add GitHub Actions CI workflow (#419)

DEV: Add GitHub Actions CI workflow (#419)

Replaces Travis CI with GitHub Actions. Provides a tighter feedback loop, within GitHub interface.

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..1fd8bb1
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,39 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        ruby:
+          - 2.4
+          - 2.5
+          - 2.6
+
+    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
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 3689fc1..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,17 +0,0 @@
-language: ruby
-sudo: false
-rvm:
-  - 2.4
-  - 2.5
-  - 2.6
-notifications:
-  email:
-    on_success: change
-    on_failure: change
-script:
-  - bundle exec rubocop
-  - bundle exec rspec
-cache:
-  bundler: true
-before_install:
-  - gem install bundler

GitHub sha: 592add52