Run CI on push only on main branch

Author: stefanistrate

.github/workflows/markdown_style_checks.yml

@@ -1,6 +1,8 @@
 name: Markdown style checks
 on:
   push:
+    branches:
+      - main
   pull_request:
   workflow_dispatch:
 jobs:

.github/workflows/python_style_checks.yml

@@ -1,6 +1,8 @@
 name: Python style checks
 on:
   push:
+    branches:
+      - main
   pull_request:
   workflow_dispatch:
 jobs:

.github/workflows/python_tests.yml

@@ -1,6 +1,8 @@
 name: Python tests
 on:
   push:
+    branches:
+      - main
   pull_request:
   workflow_dispatch:
 jobs: