Update maps submodule

Bumps [mods/ctf/ctf_map/ctf_map_core/maps](https://github.com/MT-CTF/maps) from `6afcf12` to `5915ff6`.
- [Release notes](https://github.com/MT-CTF/maps/releases)
- [Commits](MT-CTF/maps@6afcf12...5915ff6)

---
updated-dependencies:
- dependency-name: mods/ctf/ctf_map/ctf_map_core/maps
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>