Add CI and dependabot

Author: TamasSzigeti

.github/dependabot.yml

@@ -0,0 +1,16 @@
+version: 2
+updates:
+    - package-ecosystem: github-actions
+      directory: '/'
+      schedule:
+          interval: weekly
+      pull-request-branch-name:
+          separator: '-'
+    - package-ecosystem: composer
+      directory: '/'
+      versioning-strategy: widen
+      schedule:
+          interval: weekly
+      pull-request-branch-name:
+          separator: '-'
+      open-pull-requests-limit: 10

.github/workflows/continuous_integration.yml

@@ -0,0 +1,77 @@
+name: Continuous Integration
+
+on:
+  pull_request: ~
+  push:
+    branches:
+      - master
+
+jobs:
+
+  continuous-integration:
+    name: Continuous Integration
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        install-args: ['', '--prefer-lowest']
+        php-version: ['7.2', '7.3', '7.4', '8.0']
+      fail-fast: false
+
+    steps:
+      # Cancel previous runs of the same branch
+      - name: cancel
+        uses: styfle/[email protected]
+        with:
+          access_token: ${{ github.token }}
+
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Install PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: "${{ matrix.php-version }}"
+          tools: composer:v2
+
+      - name: composer-cache-dir
+        id: composercache
+        run: |
+          echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: composer-cache
+        uses: actions/[email protected]
+        with:
+          path: ${{ steps.composercache.outputs.dir }}
+          key: composer-${{ hashFiles('**/composer.json') }}-${{ matrix.install-args }}
+          restore-keys: |
+            composer-${{ hashFiles('**/composer.json') }}-${{ matrix.install-args }}
+            composer-${{ hashFiles('**/composer.json') }}-
+            composer-
+
+      - name: Install dependencies
+        run: |
+            composer update ${{ matrix.install-args }} --no-interaction --no-progress --prefer-dist
+        if: ${{ matrix.php-version != '8.0' }}
+
+      - name: Run tests with phpunit/phpunit
+        run: vendor/bin/phpunit
+
+      - name: phpstan-cache
+        uses: actions/[email protected]
+        with:
+          key: phpstan-${{ matrix.php-version }}-${{ matrix.install-args }}-${{ github.ref }}-${{ github.sha }}
+          path: .phpstan-cache
+          restore-keys: |
+            phpstan-${{ matrix.php-version }}-${{ matrix.install-args }}-${{ github.ref }}-
+            phpstan-${{ matrix.php-version }}-${{ matrix.install-args }}-
+            phpstan-${{ matrix.php-version }}-
+            phpstan-
+
+      - name: Run phpstan
+        run: composer phpstan
+
+      - name: Run php_codesniffer
+        run: composer cs-check
+        if: ${{ matrix.php-version == '7.2' }} # Do not suggest using features after 7.2