chore(ci): only run interop tests on commits to master (#5604)

## Description

This is done as temporary measure to unblock PR merging as the CI is
currently broken

Co-authored-by: Guillaume Michel <[email protected]>

Author: jxs

.github/workflows/interop-test.yml

@@ -1,6 +1,5 @@
 name: Interoperability Testing
 on:
-  pull_request:
   push:
     branches:
       - "master"