chore: avoid duplicate runs of CI in PRs

Run once for PRs, then again after merge.

Author: Byron

.github/workflows/alpine-test.yml

@@ -1,6 +1,10 @@
 name: test-alpine
 
-on: [push, pull_request, workflow_dispatch]
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
 
 permissions:
   contents: read

.github/workflows/codeql.yml

@@ -13,6 +13,7 @@ name: "CodeQL"
 
 on:
   push:
+    branches: [main]
   pull_request:
   schedule:
     - cron: '27 10 * * 3'

.github/workflows/cygwin-test.yml

@@ -1,6 +1,10 @@
 name: test-cygwin
 
-on: [push, pull_request, workflow_dispatch]
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
 
 permissions:
   contents: read

.github/workflows/lint.yml

@@ -1,6 +1,10 @@
 name: Lint
 
-on: [push, pull_request, workflow_dispatch]
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
 
 permissions:
   contents: read

.github/workflows/pythonpackage.yml

@@ -3,7 +3,11 @@
 
 name: Python package
 
-on: [push, pull_request, workflow_dispatch]
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
 
 permissions:
   contents: read