Upgrade to Nim 2.2.2

[drkameleon]

Description

Apparently, after a seemingly benign PR merge (and the subsequent CI failure lol), I realized there is a new Nim version: https://forum.nim-lang.org/t/12675

The result? LOTS of unit-tests suddenly breaking and from the initial looks of it, all having to do with floating-numbers.

But... apparently not everything is bad news. Actually, it's quite good: nim-lang/Nim@dd0cc38

Now, that means that we'll have to update the expect unit-test results. Which is fine.
But we'll have to make sure that all CI actions pull the "correct" (= 2.2.2) Nim version first. If not, we'd either have to forcefully pass the - previously default - -d:nimLegacySprintf option, or have errors.

I'd say it's worth some wait, if any.

Fixes: #1261
Fixes: #1879

Type of change

• Code cleanup
• Unit tests (added or updated unit-tests)
• Bug fix (non-breaking change which fixes an issue)

[drkameleon]

Ready to merge! 🚀