fix bug ignoring numlock when using keypad

[LB767]

Fixes imgui-rs/imgui-rs#817

I did NOT test this thoroughly!!
it works on my end but that's about it... Please do not merge unless this is fully tested

[sanbox-irl]

appreciate the warning!

[LB767]

On a sidenote, if you update this, I would personally really really really REALLY appreciate if you published a new version of imgui-rs.
I'm using an updated version of implot-rs, and I've spent a day in dependency hell with things half-working for obscure reasons which I don't even want to try and understand (like thinking it was all working except legends on implot would not register clicks). Needless to say it was infuriating, at the end of the day I could only make it work using the latest version from the git repo, so if you could just push a hotfix version like 0.12.1 it would have saved (and likely will) me a lot of headaches :)

PS: Congrats on your game it looked like a big success