Add PR trigger for the new workflow

Author: yogh333

.github/workflows/check_csdk_build_parameters.yml

@@ -1,6 +1,7 @@
 name: Build C Boilerplate application and check if C SDK build parameters are still correct
 
 on:
+  pull_request:
   workflow_dispatch:
   schedule:
     # * is a special character in YAML so you have to quote this string