Fix build on NetBSD

[0323pin]

See, GuillaumeGomez/sysinfo#625 for further details.
Updating sysinfo to 0.21.2 fixes the build

/home/pin()
2021-12-09 12:35 > version | pivot key value | to md

key	value
version	0.41.0
branch	master
short_commit	2d330f5c
commit_hash	2d330f5c77275014b24b1624045a77a52ec6bf57
commit_date	2021-12-06 21:36:34 +00:00
build_os	netbsd-x86_64
rust_version	rustc 1.57.0
cargo_version	cargo 1.57.0
pkg_version	0.41.0
build_time	2021-12-09 11:11:33 +01:00
build_rust_channel	release
features	ctrlc, dataframe, default, rustyline, term, which, zip
installed_plugins	fetch, inc, match, post, ps, sys, textview

[kubouch]

Nice, thanks!