infra github: updated the main branch name.

.github/workflows/actions_cpplint.yml

@@ -3,7 +3,7 @@ name: Check Commit
 on:
   pull_request:
     branches:
-      - master
+      - main
 
 jobs:
   coding-style:

.github/workflows/build_linux.yml

@@ -3,10 +3,10 @@ name: Linux
 on:
   pull_request:
     branches:
-      - master
+      - main
   push:
     branches:
-      - master
+      - main
 
 jobs:
   build:

.github/workflows/build_win.yml

@@ -3,10 +3,10 @@ name: Windows
 on:
   pull_request:
     branches:
-      - master
+      - main
   push:
     branches:
-      - master
+      - main
 
 jobs:
   build:

.github/workflows/codeql.yml

@@ -13,10 +13,10 @@ name: "CodeQL"
 
 on:
   push:
-    branches: [ "master" ]
+    branches: [ "main" ]
   pull_request:
     # The branches below must be a subset of the branches above
-    branches: [ "master" ]
+    branches: [ "main" ]
 
 jobs:
   analyze:

.github/workflows/regression.yml

@@ -3,7 +3,7 @@ name: Regression Testing
 on:
   pull_request:
     branches:
-      - master
+      - main
 
 jobs:
   test: