Update version support from 1.12.1 to 1.12.3

According to this commit:

https://github.com/cmangos/mangos-wotlk/commit/dca6ad0c7d952a8f928efe9199439a6e047d5dff

We'd better to update the supported version from 1.12.1 to 1.12.3;

Thank you : )