Build(deps): Bump net.fabricmc:sponge-mixin

Bumps [net.fabricmc:sponge-mixin](https://github.com/FabricMC/Mixin) from 0.13.3+mixin.0.8.5 to 0.15.2+mixin.0.8.7.
- [Commits](https://github.com/FabricMC/Mixin/commits)

---
updated-dependencies:
- dependency-name: net.fabricmc:sponge-mixin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

gradle/libs.versions.toml

@@ -7,7 +7,7 @@ neoforge = "21.1.8"
 fabric_loader = "0.15.11"
 fabric_api = "0.102.1+1.21.1"
 
-fabric_mixin = "0.13.3+mixin.0.8.5"
+fabric_mixin = "0.15.2+"
 mixinextras = "0.3.5"
 
 modsdotgroovy = "2.0.0-beta.30"