[CI] run on 1.x branch

Author: jaapio

.github/workflows/integrate.yaml

@@ -5,7 +5,7 @@ name: "Integrate"
 on: # yamllint disable-line rule:truthy
   push:
     branches:
-      - "5.x"
+      - "1.x"
   pull_request: null
   schedule:
     - cron: '0 14 * * 1'