CRAN warning

[trivialfis]

Dear maintainer,

Please see the problems shown on
https://cran.r-project.org/web/checks/check_results_xgboost.html.

Specifically, please see the NOTE about possible bashisms in the
"top-level files" check.

Fixing these should take very little time and would markedly improve
portability of your package code, so we would really appreciate if you
would fix these in the next few weeks.

Please correct before 2025-04-14 to safely retain your package on CRAN.

Best wishes,
The CRAN Team