Refine the action triggering the test CI (#143)

Signed-off-by: tdruez <tdruez@nexb.com>

Author: tdruez

.github/workflows/ci-docker.yml

@@ -1,6 +1,10 @@
 name: Test on Docker CI
 
-on: [push, pull_request]
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
 
 jobs:
   test:

.github/workflows/ci.yml

@@ -1,6 +1,10 @@
 name: Test CI
 
-on: [push, pull_request]
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
 
 env:
   DATABASE_NAME: dejacode