🔧(project) update Renovate configuration to fix match manager issue

The current Renovate configuration is using the wrong match manager, as our
project utilizes `pyproject.toml` instead of `setup.cfg`. This commit corrects
the configuration to ensure compatibility with our project structure.

renovate.json

@@ -7,7 +7,7 @@
       "enabled": false,
       "groupName": "ignored python dependencies",
       "matchManagers": [
-        "setup-cfg"
+        "pep621"
       ],
       "matchPackageNames": []
     },