Vanilla texture fix

Version 3.1 for Minecraft 1.21 - 26.1.2

Changes:

• Removed assets/minecraft/optifine directory. With this change, wall signs will have their vanilla model when using this resource pack.
• Updated pack.mcmeta

Note:

In version 3.0 I modified the model of oak doors to make them 3D and also prepare for making this change to all other doors, however I forgot to publish that version, that is why there is no such version in the version list and the change with oak doors is not mentioned anywhere.