fix: update branch references from 'main' to 'master' in CI configuration

Author: avadakedavra-wp

.github/workflows/ci.yml

@@ -2,9 +2,9 @@ name: CI
 
 on:
   push:
-    branches: [ main ]
+    branches: [ master ]
   pull_request:
-    branches: [ main ]
+    branches: [ master ]
 
 env:
   CARGO_TERM_COLOR: always