Remove snapshot repository

reactor-netty-0.6.0.RELEASE on Maven Central depends on
reactor-ipc-0.6.0.RELEASE so no need for this repository anymore.

It may be needed to cleanup Gradle or Maven local cache
since preliminary version of reactor-netty-0.6.0.RELEASE
had a dependency on reactor-ipc-0.6.0.BUILD-SNAPSHOT.

build.gradle

@@ -172,7 +172,6 @@ configure(allprojects) { project ->
 	repositories {
 		maven { url "https://repo.spring.io/libs-release" }
 		maven { url "https://repo.spring.io/milestone" }
-		maven { url "https://repo.spring.io/snapshot" } // reactor-netty still pulls reactor-ipc 0.6 snapshots
 	}
 
 	dependencies {