ci: Trigger airflow workflow on PR for testing

Author: Techassi

.github/workflows/dev_airflow.yaml

@@ -5,6 +5,8 @@ env:
   PRODUCT_NAME: airflow
 
 on:
+  # For temporary testing
+  pull_request:
   workflow_dispatch:
   schedule:
     - cron: '0 1 1/2 * *' # https://crontab.guru/#0_1_1/2_*_*