Disable renovate branch builds (#753)

Renovate PRs currently trigger 2 builds:

- For the PR itself
- For the `renovate/...` branch

This only increases builds without any benefit.

Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/753
Co-authored-by: justusbunsi <sk.bunsenbrenner@gmail.com>
Co-committed-by: justusbunsi <sk.bunsenbrenner@gmail.com>

.gitea/workflows/test-pr.yml

@@ -7,7 +7,6 @@ on:
   push:
     branches:
       - main
-      - "renovate/**"
 
 env:
   # renovate: datasource=github-releases depName=helm-unittest/helm-unittest