Bump minimum required version of symfony/serializer

to fix installation on never versions of Drupal core.

Also adjust minimum version requirement for other Symfony packages.

composer.json

@@ -28,10 +28,10 @@
         "php-http/message-factory": "^1.0",
         "phpdocumentor/reflection-docblock": "^5.0",
         "psr/http-message": "^1.0 || ^2.0",
-        "symfony/options-resolver": "^6.4.6",
-        "symfony/property-access": "^6.4.6",
-        "symfony/property-info": "^6.4.6",
-        "symfony/serializer": "^6.4.6"
+        "symfony/options-resolver": "^6.4.9",
+        "symfony/property-access": "^6.4.9",
+        "symfony/property-info": "^6.4.9",
+        "symfony/serializer": "^6.4.9"
     },
     "require-dev": {
         "dms/phpunit-arraysubset-asserts": "^0.4.0",
@@ -46,12 +46,9 @@
         "phpmetrics/phpmetrics": "^2.7",
         "phpunit/phpunit": "^9.6",
         "sebastian/comparator": "^4.0.5",
-        "symfony/cache": "^6.4.6",
+        "symfony/cache": "^6.4.9",
         "vimeo/psalm": "^5.20"
     },
-    "conflict": {
-        "symfony/serializer": ">6.4.6"
-    },
     "autoload": {
         "psr-4": {
             "Apigee\\Edge\\": "src"