Use the 'branch' auto merge type in renovate's configuration.

Instead of crating MRs, renovate will:

- Create the branch, wait for test results
- Rebase it any time it gets out of date with the base branch
- Automerge the branch commit if it's:
    (a) up-to-date with the base branch, and
    (b) passing all tests
- As a backup, raise a PR only if either:
    (a) tests fail, or
    (b) tests remain pending for too long (default: 24 hours)

Resolves #62

Signed-off-by: Miguel Martín <mmartinv@redhat.com>

.tekton/fedora-bootc-42-standard-push.yaml

@@ -10,6 +10,7 @@ metadata:
     pipelinesascode.tekton.dev/on-cel-expression: |
       event == "push" &&
       (
+        target_branch.matches("renovate/.*") ||
         target_branch == "main"
       ) && (
         ".tekton/fedora-bootc-42-standard-push.yaml".pathChanged() ||