Fix CI to run tests for python (#52)

fix ci

.github/workflows/ci.yml

@@ -5,10 +5,10 @@ on:
   push:
     branches: [ main ]
     paths:
-      - '!frontend/**'
+      - 'backend/**'
   pull_request:
     paths:
-      - '!frontend/**'
+      - 'backend/**'
   workflow_dispatch:  # Allows to trigger the workflow manually in GitHub UI
 
 # If another push to the same PR or branch happens while this workflow is still running,