Move to Github Actions from Travis CI

Add the following workflows:
- Unit Tests - phpunit
- Coding Standards - phpcs
- Coverage - run tests with coverage and upload to coveralls

.github/workflows/coverage.yml

@@ -0,0 +1,29 @@
+name: Coverage
+
+on: [push, pull_request]
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 7.4
+
+      - name: Install dependencies
+        run: composer install --no-progress --no-suggest --optimize-autoloader
+
+      - name: Add coveralls dependency
+        run: composer require --dev php-coveralls/php-coveralls --no-progress --no-suggest --no-interaction
+
+      - name: Run tests with coverage
+        run: composer test-coverage
+
+      - name: Upload coverage to Coveralls
+        env:
+          COVERALLS_REPO_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: php vendor/bin/php-coveralls -v

.github/workflows/phpcs.yml

@@ -0,0 +1,24 @@
+name: Coding Standards
+
+on: [push, pull_request]
+
+jobs:
+  phpcs:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 7.4
+
+      - name: Validate composer.json
+        run: composer validate --strict
+
+      - name: Install dependencies
+        run: composer install --no-progress --no-suggest --optimize-autoloader
+
+      - name: Run CS checks
+        run: composer cs-check

.github/workflows/phpunit.yml

@@ -0,0 +1,31 @@
+name: Unit Tests
+
+on: [push, pull_request]
+
+jobs:
+  phpunit:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      max-parallel: 15
+      matrix:
+        dependencies: ['lowest', 'latest']
+        php-versions: ['7.3', '7.4', '8.0']
+    name: PHP ${{ matrix.php-versions }}, ${{ matrix.dependencies }} dependencies
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+
+      - name: Install dependencies
+        env:
+          DEPS: ${{ matrix.dependencies }}
+        run: |
+          if [[ $DEPS != 'lowest' ]]; then composer update --no-progress --no-suggest --prefer-lowest --prefer-stable --optimize-autoloader ; else composer update --no-progress --no-suggest --prefer-dist --optimize-autoloader ; fi
+
+      - name: Run tests
+        run: composer test

README.md

@@ -1,6 +1,7 @@
 # Webimpress Coding Standard
 
-[![Build Status](https://travis-ci.com/webimpress/coding-standard.svg?branch=master)](https://travis-ci.com/webimpress/coding-standard)
+[![Unit Tests](https://github.com/webimpress/coding-standard/actions/workflows/phpunit.yml/badge.svg)](https://github.com/webimpress/coding-standard/actions/workflows/phpunit.yml)
+[![Coding Standards](https://github.com/webimpress/coding-standard/actions/workflows/phpcs.yml/badge.svg)](https://github.com/webimpress/coding-standard/actions/workflows/phpcs.yml)
 [![Coverage Status](https://coveralls.io/repos/github/webimpress/coding-standard/badge.svg?branch=master)](https://coveralls.io/github/webimpress/coding-standard?branch=master)
 
 ## Installation