fix: disable strict mode in renovate config validator

Strict mode causes failures when a config migration is available.

Author: claude

.github/workflows/renovate-config-validator.yml

@@ -15,3 +15,5 @@ jobs:
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
       - uses: deviantintegral/github-action-renovate-config-validator@322e333e6885127adce1185bf8a377a3fd053c66 # fix-latest-version
+        with:
+          strict: false