chore(renovate): update config (#11490)

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/11490
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: Michael Kriese <michael.kriese@visualon.de>
Co-committed-by: Michael Kriese <michael.kriese@visualon.de>

.forgejo/renovate.json

@@ -13,7 +13,8 @@
   ],
   "postUpdateOptions": ["gomodTidy", "gomodUpdateImportPaths", "npmDedupe"],
   "prConcurrentLimit": 10,
-  "osvVulnerabilityAlerts": true,
+  "dependencyDashboardReportAbandonment": false,
+  "dependencyDashboardHeader": "This issue lists Renovate updates and detected dependencies. Read the [Dependency Dashboard](https://docs.renovatebot.com/key-concepts/dashboard/) docs to learn more.\n- [ ] <!-- manual job -->Check this box to trigger a request for Renovate to run again on this repository\n",
   "automergeStrategy": "squash",
   "labels": ["dependency-upgrade", "test/not-needed"],
   "packageRules": [