Fix update-minecraft-src.sh script for MacOS

[Morb0]

Summary

• Fix sed -i compatibility in update-minecraft-src.sh for macOS
  • macOS sed requires a backup extension argument, unlike GNU sed
  • Use sed -i.bak which works on both macOS and Linux

[4lve]

I'm not sure if this version pinning is required anymore with the latest GitCraft version. Could you try removing it completely?

[Morb0]

I'm not sure if this version pinning is required anymore with the latest GitCraft version. Could you try removing it completely?

Removed the groovy version pin - you were right, it's not needed anymore.
But there was other issue with loom_version = 1.+ resolving to 1.16.0-alpha.16, which changed TinyJavadocProvider constructor API and broke the build.
So I pinned loom_version to 1.15.5 (latest stable) instead.