gnucompability(date): hence is not supported by uu

[HackingRepo]

Hi, uutils mainteners

we saw that when trying

relunsec@relunsec:~/software/coreutils/target/debug$ ./date -d "2 months hence"
date: invalid date '2 months hence'
relunsec@relunsec:~/software/coreutils/target/debug$ gnudate -d "2 months hence"
Wed Nov 18 10:25:30 AM EST 2026
relunsec@relunsec:~/software/coreutils/target/debug$ 

that is not just a feature request that more because that from the intial gnu release not a new gnu feature