Use PHPUnit ^9.3 on PHP 8.0

Author: GrahamCampbell

.github/workflows/tests.yml

@@ -35,6 +35,14 @@ jobs:
           command: composer update --no-interaction --no-progress
         if: "matrix.php < 8"
 
+      - name: Setup PHP 8 Dependencies
+        uses: nick-invision/retry@v1
+        with:
+          timeout_minutes: 5
+          max_attempts: 5
+          command: composer require "phpunit/phpunit:^9.3" --no-interaction --no-update
+        if: "matrix.php >= 8"
+
       - name: Install PHP 8 Dependencies
         uses: nick-invision/retry@v1
         with:

composer.json

@@ -37,5 +37,7 @@
         "branch-alias": {
             "dev-master": "1.7-dev"
         }
-    }
+    },
+    "minimum-stability": "dev",
+    "prefer-stable": true
 }