chore(renovate): always set the test/not-needed label

Under the assumption that all dependencies have at least some test
coverage. It may not be always true but it is generally true. Ideally
there would be an inventory, a checklist of dependencies that miss
test coverage, but that does not exist.

renovate.json

@@ -16,7 +16,7 @@
   "prConcurrentLimit": 10,
   "osvVulnerabilityAlerts": true,
   "automergeStrategy": "squash",
-  "labels": ["dependency-upgrade"],
+  "labels": ["dependency-upgrade","test/not-needed"],
   "packageRules": [
     {
       "description": "Require approval for python minor version",