Fix: 1. Emoji fields in SelectMenuOption and Button structs are optional. 2. Swap height and width variables

[nek0peko]

Problem: https://github.com/bwmarrin/discordgo/issues/1474

This will render the '/imagine_settings' command unusable.

New release version (v0.26.3) of discordgo has solved the problem.

This pull request just simply changes the version.

[nek0peko]

Then run the command below to update go.sum

go get -u