Bump com.github.johnrengelman.shadow from 7.1.2 to 8.1.1

Bumps com.github.johnrengelman.shadow from 7.1.2 to 8.1.1.

---
updated-dependencies:
- dependency-name: com.github.johnrengelman.shadow
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

build.gradle.kts

@@ -3,7 +3,7 @@ import io.papermc.paperweight.util.constants.*
 plugins {
     java
     `maven-publish`
-    id("com.github.johnrengelman.shadow") version "7.1.2" apply false
+    id("com.github.johnrengelman.shadow") version "8.1.1" apply false
     id("io.papermc.paperweight.patcher") version "1.3.11"
 }