ci: adopt shared renovate config

Author: jGleitz

renovate.json

@@ -0,0 +1,13 @@
+{
+  /* Simulate this configuration locally by running:
+     podman run --rm \
+         --mount type=bind,src="$(pwd)",dst=/repo \
+         --workdir /repo \
+         --user 0 \
+         --env RENOVATE_GITHUB_COM_TOKEN=$(secret-tool lookup service renovate-dry-run) \
+         --env LOG_LEVEL=debug \
+         renovate/renovate --dry-run=full --platform=local
+  */
+  $schema: "https://docs.renovatebot.com/renovate-schema.json",
+  extends: ["github>jGleitz/renovate-config:default.json5"],
+}