Change deployment branch from 'main' to 'master'

Signed-off-by: Yunsup Sim <dev@ethansup.net>

Author: SimYunSup

.github/workflows/deploy.yml

@@ -2,7 +2,8 @@ name: Deploy to GitHub Pages
 
 on:
   push:
-    branches: [ main ]
+    branches: [ master ]
+  workflow_dispatch:
 
 permissions:
   contents: read