Updated compatibility workflow

Author: chinefed

.github/workflows/compatibility.yml

@@ -2,13 +2,17 @@ name: Compatibility tests
 
 on:
   push:
+    branches:
+      - main
     paths:
       - pyproject.toml
       - tox.ini
       - tests/**
       - .github/workflows/compatibility.yml
       - dna2graph/**
   pull_request:
+    branches:
+      - main
     paths:
       - pyproject.toml
       - tox.ini