Run workflows on pull request, as we are not using SKARA.

Author: gnu-andrew

.github/workflows/main.yml

@@ -30,7 +30,7 @@ on:
     branches-ignore:
       - master
       - pr/*
-  workflow_dispatch:
+  pull_request:
     inputs:
       platforms:
         description: 'Platform(s) to execute on (comma separated, e.g. "linux-x64, macos, aarch64")'