net/mpich: Update 4.3.1 => 4.3.2
Changelog:
https://www.mpich.org/2025/10/06/mpich-4-3-2-released/
- Switch repo to github because of Cloudflare "JS challenge" issues with fetch on the mpich.org domain.
- Replace space with tab in CONFIGURE_ARGS.
PR: 290082
MFH: 2025Q4