ci(renovate): Adjust config for tekton updates

renovate.json

@@ -357,9 +357,14 @@
       }
     },
     {
-      "matchFileNames": [
-        "apps/base/tekton/mirror-releases\\.sh$"
+      "matchPackageNames": [
+        "tektoncd/pipeline",
+        "tektoncd/triggers"
+      ],
+      "matchDatasources": [
+        "github-releases"
       ],
+      "groupName": "github/tekton",
       "postUpgradeTasks": {
         "commands": [
           "./apps/base/tekton/mirror-releases.sh"