Update composer.json

Allow newer versions of phpunit-bridge

Author: thirsch

composer.json

@@ -27,7 +27,7 @@
     },
     "require-dev": {
         "mockery/mockery": "^1.0",
-        "symfony/phpunit-bridge": "^4.4|^5.4"
+        "symfony/phpunit-bridge": "^4.4|^5.4|^6|^7"
     },
     "replace": {
         "swiftmailer/swiftmailer": "^6"