GitHub Actions: Only run build when pushing or PR'ing to master branch

.github/workflows/cmake_linux.yml

@@ -3,6 +3,7 @@ name: CMake (Linux)
 on:
 
   push:
+    branches: [ "master" ]
     paths:
       - src/**
       - cmake/**
@@ -14,6 +15,7 @@ on:
       - "!**/Makefile*"
 
   pull_request:
+    branches: [ "master" ]
     paths:
       - src/**
       - cmake/**

.github/workflows/cmake_macos.yml

@@ -3,6 +3,7 @@ name: CMake (macos)
 on:
 
   push:
+    branches: [ "master" ]
     paths:
       - src/**
       - cmake/**
@@ -14,6 +15,7 @@ on:
       - "!**/Makefile*"
 
   pull_request:
+    branches: [ "master" ]
     paths:
       - src/**
       - cmake/**

.github/workflows/cmake_windows_msys2.yml

@@ -3,6 +3,7 @@ name: CMake (Windows, msys2)
 on:
 
   push:
+    branches: [ "master" ]
     paths:
       - src/**
       - cmake/**
@@ -14,6 +15,7 @@ on:
       - "!**/Makefile*"
 
   pull_request:
+    branches: [ "master" ]
     paths:
       - src/**
       - cmake/**