Add github actions

Author: sagikazarmark

.github/workflows/.editorconfig

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+[*.yml]
+indent_size = 2

.github/workflows/checks.yml

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+name: Checks
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  composer-normalize:
+    name: Composer Normalize
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v1
+
+      - name: Install
+        uses: docker://composer
+        with:
+          args: install
+
+      - name: Normalize
+        uses: docker://composer
+        with:
+          args: composer normalize --dry-run
+
+  roave-bc-check:
+    name: Roave BC Check
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v1
+
+      - name: Roave BC Check
+        uses: docker://nyholm/roave-bc-check-ga

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  build-lowest-version:
+    name: Build lowest version
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Set up PHP
+        uses: shivammathur/setup-php@1.6.2
+        with:
+          php-version: '7.1'
+          coverage: xdebug
+          extensions: mbstring
+
+      - name: Setup Problem Matchers for PHPUnit
+        run: echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
+
+      - name: Checkout code
+        uses: actions/checkout@v1
+
+      - name: Download dependencies
+        run: composer update --prefer-stable --prefer-dist --no-interaction --no-progress --no-suggest --prefer-lowest
+
+      - name: Run tests
+        run: composer test-ci
+
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    strategy:
+      max-parallel: 10
+      matrix:
+        php: ['7.1', '7.2', '7.3', '7.4']
+
+    steps:
+      - name: Set up PHP
+        uses: shivammathur/setup-php@1.6.2
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: mbstring
+
+      - name: Setup Problem Matchers for PHPUnit
+        run: echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
+
+      - name: Checkout code
+        uses: actions/checkout@v1
+
+      - name: Download dependencies
+        run: composer update --prefer-stable --prefer-dist --no-interaction --no-progress --no-suggest
+
+      - name: Run tests
+        run: composer test

.github/workflows/static.yml

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+name: Static analysis
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  phpstan:
+    name: PHPStan
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v1
+
+      - name: PHPStan
+        uses: docker://oskarstark/phpstan-ga
+        with:
+          args: analyze --no-progress
+
+  php-cs-fixer:
+    name: PHP-CS-Fixer
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v1
+
+      - name: PHP-CS-Fixer
+        uses: docker://oskarstark/php-cs-fixer-ga
+        with:
+          args: --dry-run --diff-format udiff