Update dependency symfony/var-dumper to v8

| datasource | package            | from  | to    |
| ---------- | ------------------ | ----- | ----- |
| packagist  | symfony/var-dumper | 7.3.5 | 8.0.0 |


Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

composer.json

@@ -33,7 +33,7 @@
         "phpstan/phpstan": "^2.1.16",
         "phpunit/phpunit": "^12.1.5",
         "roave/security-advisories": "dev-master",
-        "symfony/var-dumper": "^6.4.0 || ^7.0.0",
+        "symfony/var-dumper": "^8.0.0",
         "wnx/commonmark-markdown-renderer": "^1.4"
     },
     "config": {