Update Horcrux go.mod module path

[jakubbujny]

Horcrux is currently at major version 3.X From golang perspective module path should be updated to contain v3 in path, ref: https://go.dev/doc/modules/version-numbers#major

A major version update to a number higher than v1 will also have a new module path. That’s because the module path will have the major version number appended, as in the following example: module example.com/mymodule/v2 v2.0.0