chore: update CI workflows to use main branch instead of master (#680)

- Remove master branch references from build-native.yml
- Update snapshot.yml to trigger on main branch
- Remove master branch references from test.yml

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: xerial

.github/workflows/build-native.yml

@@ -4,7 +4,6 @@ on:
   workflow_dispatch:
   push:
     branches:
-      - master
       - main
     paths:
       - 'src/main/resources/org/xerial/snappy/VERSION'

.github/workflows/snapshot.yml

@@ -3,7 +3,7 @@ name: Snapshot Release
 on:
   push:
     branches:
-      - master
+      - main
     paths:
       - '**.scala'
       - '**.java'

.github/workflows/test.yml

@@ -4,7 +4,6 @@ on:
   pull_request:
   push:
     branches:
-      - master
       - main
 
 jobs: