chore: add revdep directory to .gitignore

- Exclude revdepcheck output directory from version control
- This directory is generated during reverse dependency checks

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

Co-Authored-By: Claude <noreply@anthropic.com>

Author: elong0527

.gitignore

@@ -9,3 +9,4 @@ sync_bitbucket.R
 r2rtf.Rcheck/
 r2rtf*.tar.gz
 r2rtf*.tgz
+revdep/