science/mmg: Update 5.7.3 => 5.8.0, take maintainership

[alven]

Summary

Changelogs:

• https://github.com/MmgTools/mmg/releases/tag/v5.8.0
• https://github.com/MmgTools/mmg/compare/v5.7.3...v5.8.0

• Add WWW for source code repository
• Clarify LICENSE and pkg-descr
• Pet portclippy(1) and portfmt(1)
• Bash is still needed for running some configure script - scripts/git_log_mmg.sh, so is patching it with shebangfix

Test Plan

For every {amd64} × {14.3, 13.5}:

• Successful poudriere testport
• Successful run-testing

[yuri]

Approved.

Thanks,
Yuri