Bump external/imgui-filebrowser from b8fedfb to 60d4e09

Bumps [external/imgui-filebrowser](https://github.com/AirGuanZ/imgui-filebrowser) from `b8fedfb` to `60d4e09`.
- [Commits](AirGuanZ/imgui-filebrowser@b8fedfb...60d4e09)

---
updated-dependencies:
- dependency-name: external/imgui-filebrowser
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>