Please put Mixins into "client" section of Mixin Config

[shartte]

https://github.com/Chisel-Team/ConnectedTexturesMod/blob/19a58b080ff2d4fec4fd44ffdb426fc078ce853d/src/main/resources/ctm.mixins.json#L5

Changing this client instead of mixins prevents the server from trying to load a client class if CTM is present.