Fix integration.yml

Don't run twice the workflow on PR opened from the same repository.

.github/workflows/integration.yml

@@ -1,6 +1,10 @@
 name: Integration
 
-on: [push, pull_request]
+on:
+  push:
+    branches: ["master"]
+  pull_request:
+    branches: ["master"]
 
 jobs:
   python: