Replace Travis CI with GitHub Actions

 # Conflicts:
 #	.travis.yml

.github/workflows/test.yml

@@ -0,0 +1,32 @@
+name: Tests and linting
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Validate composer.json and composer.lock
+        run: composer validate --strict
+
+      - name: Cache Composer packages
+        id: composer-cache
+        uses: actions/cache@v2
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php-
+
+      - name: Install dependencies
+        run: composer install --prefer-dist --no-progress
+
+      - name: Run linting
+        run: composer run-script lint
+
+      - name: Run tests
+        run: composer run-script test

composer.json

@@ -32,5 +32,9 @@
         "branch-alias": {
             "dev-master": "1.x-dev"
         }
+    },
+    "scripts": {
+        "lint": "vendor/bin/phpcs --standard=PSR12 src/",
+        "test": "vendor/bin/phpspec run -f pretty"
     }
 }