Migrate the CI and deployment to GitHub Actions.

.github/workflows/ci.yml

@@ -0,0 +1,20 @@
+name: CI
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.4.4
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+      - name: Build
+        run: bundle exec jekyll build

.github/workflows/deploy.yml

@@ -0,0 +1,26 @@
+name: Deploy
+on:
+  push:
+    branches:
+      - master
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.4.4
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+      - name: Build
+        run: bundle exec jekyll build
+      - name: Deploy
+        uses: burnett01/[email protected]
+        with:
+          switches: -avz
+          path: _site/
+          remote_path: www/
+          remote_host: ${{ secrets.DEPLOY_HOST }}
+          remote_user: ${{ secrets.DEPLOY_USER }}
+          remote_key: ${{ secrets.DEPLOY_KEY }}