[pr-66] fix: make old_line and new_line optional for image diff discussions

🐛 Bug Fix:
- Image files in GitLab MR discussions use x/y coordinates instead of line numbers
- Fixed schema validation error when fetching discussions on image files

📝 Details:
- Changed old_line and new_line from required to optional in GitLabDiscussionNoteSchema
- Allows proper handling of image diff comments that use position_type: 'image'

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@zereight/mcp-gitlab",
-  "version": "1.0.53",
+  "version": "1.0.52",
   "description": "MCP server for using the GitLab API",
   "license": "MIT",
   "author": "zereight",