Update build dependencies

build.gradle.kts

@@ -1,20 +1,11 @@
 plugins {
     base
-    idea
-    kotlin("jvm") version embeddedKotlinVersion apply false
-    kotlin("kapt") version embeddedKotlinVersion apply false
-    id("com.github.johnrengelman.shadow") version "5.2.0" apply false
-    id("org.ajoberstar.stutter") version "0.5.1" apply false
 }
 
 group = "org.nixos.gradle2nix"
 version = property("VERSION") ?: "unspecified"
 
 subprojects {
-    repositories {
-        jcenter()
-        maven { url = uri("https://repo.gradle.org/gradle/libs-releases") }
-    }
     group = rootProject.group
     version = rootProject.version
 }
@@ -40,7 +31,7 @@ allprojects {
                     file("gradle.lockfile").delete()
                 }
                 doLast {
-                    configurations.matching { it.isCanBeResolved}.all { resolve() }
+                    configurations.matching { it.isCanBeResolved }.all { resolve() }
                 }
             }
         }
@@ -49,7 +40,7 @@ allprojects {
 
 tasks {
     wrapper {
-        gradleVersion = "6.8-rc-1";
+        gradleVersion = "6.8.1"
         distributionType = Wrapper.DistributionType.ALL
     }
 }