gha: only run on pushes to master

Otherwise on `pull_request` it is

Author: mfn

.github/workflows/analysis.yml

@@ -3,6 +3,8 @@ name: Code Analysis
 on:
   pull_request:
   push:
+    branches:
+      - master
   schedule:
     # Run Monday morning at 3 o'clock
     #       ┌───────────── minute (0 - 59)

.github/workflows/integration_tests.yml

@@ -3,6 +3,8 @@ name: Integration tests
 on:
   pull_request:
   push:
+    branches:
+      - master
   schedule:
     # Run Monday morning at 3 o'clock
     #       ┌───────────── minute (0 - 59)

.github/workflows/tests.yml

@@ -3,6 +3,8 @@ name: Tests
 on:
   pull_request:
   push:
+    branches:
+      - master
   schedule:
     # Run Monday morning at 3 o'clock
     #       ┌───────────── minute (0 - 59)