feat: add github actions test for upcoming symfony version

Author: Chris53897

.github/workflows/tests-upcoming-symfony.yaml

@@ -0,0 +1,40 @@
+# OS: Linux; Symfony: upcoming (still unreleased) version; PHP: latest stable
+name: "Tests - Upcoming Symfony version (allowed to fail !)"
+
+on: ["push", "pull_request"]
+
+env:
+  fail-fast: true
+
+jobs:
+  tests:
+    runs-on: 'ubuntu-latest'
+    continue-on-error: true
+    steps:
+      - name: 'Checkout code'
+        uses: actions/checkout@v2.3.3
+
+      - name: 'Install PHP with extensions'
+        uses: shivammathur/setup-php@2.7.0
+        with:
+          coverage: none
+          php-version: '8.0'
+          tools: composer:v2
+          extensions: mbstring
+          ini-values: date.timezone=UTC
+
+      - name: 'Install project dependencies'
+        env:
+          SYMFONY_REQUIRE: '6.0.x@dev'
+        run: |
+          composer global require --no-progress --no-scripts --no-plugins symfony/flex
+          composer require symfony/phpunit-bridge
+          composer config minimum-stability dev
+          composer config prefer-stable false
+          composer update --no-interaction --optimize-autoloader
+
+      - name: 'Run tests'
+        env:
+          SYMFONY_DEPRECATIONS_HELPER: 'weak'
+          #SYMFONY_DEPRECATIONS_HELPER: 'max[indirect]=9999&max[direct]=0&max[self]=9999'
+        run: vendor/bin/phpunit -v || exit 0