numfmt: should use lowercase k with --to=si option #7221
Description
Environment: Ubuntu 24.04, uutils main branch (git commit 2430e2a), GNU coreutils v9.6.8-fbfd88-dirty
Steps to reproduce:
numfmt --to=si 2000
What happens now: uutils numfmt uses uppercase K:
2.0K
What I expected to happen: GNU numfmt uses lowercase k:
2.0k
Notes: this is causing a test failure in GNU test file tests/misc/numfmt.pl.