[repo] Update the shadow version to 8.1.1 release

https://github.com/johnrengelman/shadow/releases/tag/8.1.1

kotlin-native/tools/performance-server/ui/buildSrc/build.gradle.kts

@@ -65,7 +65,7 @@ dependencies {
     val kotlinVersion = project.bootstrapKotlinVersion
     val ktorVersion = "1.2.1"
     val slackApiVersion = "1.2.0"
-    val shadowVersion = "7.1.2"
+    val shadowVersion = "8.1.1"
     val metadataVersion = "0.0.1-dev-10"
 
     implementation("org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion")
@@ -81,6 +81,6 @@ dependencies {
 
     // Located in <repo root>/shared and always provided by the composite build.
     //api("org.jetbrains.kotlin:kotlin-native-shared:$konanVersion")
-    implementation("gradle.plugin.com.github.johnrengelman:shadow:$shadowVersion")
+    implementation("com.github.johnrengelman:shadow:$shadowVersion")
     implementation("org.jetbrains.kotlinx:kotlinx-metadata-klib:$metadataVersion")
 }