ci: add temporary push trigger for workflow testing

Signed-off-by: Henri Rosten <henri.rosten@unikie.com>

Author: henrirosten

.github/workflows/update-flake-inputs.yml

@@ -5,6 +5,10 @@
 name: Update flake inputs and Jenkins plugins
 
 on:
+  # Temporary trigger to test this workflow (including PR creation) before merge.
+  push:
+    branches:
+      - periodic-flake-update
   schedule:
     # 06:00 EET (UTC+2) every Monday
     - cron: "0 4 * * 1"