Revert "Use plugins-release"

This reverts commit 9a2c184c9f.

This caused a problem with the snapshot build, reverting
while I find an approach that works for community usage

build.gradle

@@ -8,7 +8,7 @@ buildscript {
 		classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
 	}
 	repositories {
-		maven { url 'https://repo.spring.io/plugins-release' }
+		maven { url 'https://repo.spring.io/plugins-snapshot' }
 		maven { url 'https://plugins.gradle.org/m2/' }
 	}
 }