release: bump version to 1.15.90 (1.16-rc1)

4 jobs for nm-1-16 in 82 minutes and 5 seconds (queued for 4 minutes and 9 seconds)
Status Job ID Name Coverage
  Test
passed #135578
build_f28

00:41:35

passed #135579
build_f_latest

00:41:27

passed #135580
build_f_rawhide

00:30:29

passed #135577
checkpatch

00:05:56