add PHP 8 support

.editorconfig

@@ -0,0 +1,18 @@
+; This file is for unifying the coding style for different editors and IDEs.
+; More information at http://editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 4
+trim_trailing_whitespace = true
+
+[*.md]
+trim_trailing_whitespace = false
+
+[*.yml]
+indent_size = 2

.github/workflows/tests.yml

@@ -0,0 +1,40 @@
+name: Tests
+
+on: ['push', 'pull_request']
+
+jobs:
+  ci:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        php: ['7.3', '7.4', '8.0']
+        dependency-version: [prefer-lowest, prefer-stable]
+
+    name: PHP ${{ matrix.php }} - ${{ matrix.os }} - ${{ matrix.dependency-version }}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          tools: composer:v2
+          coverage: none
+
+      - name: Setup Problem Matches
+        run: |
+          echo "::add-matcher::${{ runner.tool_cache }}/php.json"
+          echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
+      - name: Install PHP 7 dependencies
+        run: composer update --${{ matrix.dependency-version }} --no-interaction --no-progress
+        if: "matrix.php < 8"
+
+      - name: Install PHP 8 dependencies
+        run: composer update --${{ matrix.dependency-version }} --ignore-platform-req=php --no-interaction --no-progress
+        if: "matrix.php >= 8"
+
+      - name: Tests
+        run: php bin/pest --colors=always

.gitignore

@@ -1,2 +1,3 @@
 /vendor/
 composer.lock
+.phpunit.result.cache