Update version constant to 2.6.0

[Nytra]

Current value of 2.5.1 is wrong afaik

MonkeyLoader.GamePacks.ResoniteModLoader/MonkeyLoader.GamePacks.ResoniteModLoader/ModLoader.cs

Line 30 in b7b6464

internal const string VERSION_CONSTANT = "2.5.1";

[Nytra]

This causes ResoniteIKCulling to not patch anything because it thinks the version is out of date

[INFO] [MonkeyLoader|ResoniteIKCulling] Mod loader version out of date, please update to version 2.6.0 or later

[Banane9]

Oh huh - we'll need to check if any of the public api changed then. I still wanted to make a tool for that since I didn't find one, but never got to it 😂

[Banane9]

Right... we were already doing the right version, but just didn't have it set in the constant 🤪