Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/mxt-app/versions.

Version release notes (from GitHub):
Changes since v1.27
- Added broken line test for sensors
- Added Sensor Variant Algorithm test for sensors
- Added .empty in m4 folder and removed mkdir in autogen.sh
- Fix mxt_convert_hex_test on 32 bit architectures
- Fixed uninitialized variable ctx->active_stylus
- Fixed extended config byte returning zeros
- Other minor fixes

These checks were done:

- built on NixOS
- /nix/store/1769xizqkbd8dd6llqy02rldci3pwijk-mxt-app-1.28/bin/mxt-app passed the binary check.
- 1 of 1 passed binary check by having a zero exit code.
- 1 of 1 passed binary check by having the new version present in output.
- found 1.28 with grep in /nix/store/1769xizqkbd8dd6llqy02rldci3pwijk-mxt-app-1.28
- directory tree listing: https://gist.github.com/fc84545295cbe4aa871675e481f9d678
- du listing: https://gist.github.com/3f8880133bd987a4e81d820e8ae6a5b4

never built on darwin

mxt-app: 1.27 -> 1.28