Mark 1.21 versions of `Updating World Icon` as compatible with 1.21.1

1.21.1 is no different from 1.21 according to Mojang, so why not mark Updating World Icon 1.0.1 for 1.21 (Fabric and NeoForge) as compatible with 1.21.1?

1.21.1 is a popular version for mods, as 1.20.1 and 1.19.2 were and are now.