free: fix humanization

[Bluemangoo]

• fix free: implement --human #73

$ cargo run -q free -h && free -h && free
               total        used        free      shared  buff/cache   available
Mem:            29Gi        13Gi       2.2Gi       2.4Gi        15Gi        15Gi
Swap:           22Gi          0B        22Gi
               total        used        free      shared  buff/cache   available
Mem:            29Gi        13Gi       2.2Gi       2.4Gi        15Gi        15Gi
Swap:           22Gi          0B        22Gi
               total        used        free      shared  buff/cache   available
Mem:        30517772    14584340     2340712     2487436    16534996    15933432
Swap:       23437308           0    23437308

tips: this is what procps actually doing, weird

10138 * 1024 B -> "9.9Mi"
10230 * 1024 B -> "9Mi"

plus, humanization of procps differs from coreutils'. coreutils' use ceil.

[Krysztal112233]

looks great :)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.00%. Comparing base (f3860a7) to head (bf69bef).
Report is 5 commits behind head on main.

Additional details and impacted files

@@     Coverage Diff     @@
##   main   #431   +/-   ##
===========================
===========================

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.