script/generate-versions: fix versions sort

[dgrisonnet]

Description

I was wondering why kube-state-metrics wasn't updated from v2.9.2 to v2.10.z despite these new releases out for a couple a few months, and it seems that the script was buggy.

Instead of using -n option we should use -V which is meant for sorting versions.

➜  ~ printf '%s\n' "9" "10" | sort -V -r 
10
9
➜  ~ printf '%s\n' "2.9.2" "2.10.1" | sort -V -r
2.10.1
2.9.2

This new version also fixes the problem reported in #2261.

Type of change

What type of changes does your code introduce to the kube-prometheus? Put an x in the box that apply.

• CHANGE (fix or feature that would cause existing functionality to not work as expected)
• FEATURE (non-breaking change which adds functionality)
• BUGFIX (non-breaking change which fixes an issue)
• ENHANCEMENT (non-breaking change which improves existing functionality)
• NONE (if none of the other choices apply. Example, tooling, build system, CI, docs, etc.)

Changelog entry

Please put a one-line changelog entry below. Later this will be copied to the changelog file.

[dgrisonnet]

cc @philipgough

If this change didn't make it to the next trigger of the script, would you mind to retrigger it manually? 🙇

[philipgough]

lgtm