lang/janet: update to v1.28.0

[hsw_bitmark.com]

Summary

update port lang/janet to 1.28.0

Test Plan

Test and build on 13.1 and 13.2

poudriere testport -i -j 13_1-amd64 lang/janet
poudriere bulk -j 13_1-amd64 lang/janet
poudriere testport -i -j 13_2-amd64 lang/janet
poudriere bulk -j 13_2-amd64 lang/janet

Install resulting 13.1 package on host system then compile and test some janet code
toi make sure packge extracts and runs correctly.

[arrowd]

Pushed, thanks.