Point to samples on 5.6.x branch

gradle.properties

@@ -5,7 +5,7 @@ springFrameworkVersion=5.3.13
 openSamlVersion=3.4.6
 version=5.6.1-SNAPSHOT
 kotlinVersion=1.5.31
-samplesBranch=main
+samplesBranch=5.6.x
 org.gradle.jvmargs=-Xmx3g -XX:MaxPermSize=2048m -XX:+HeapDumpOnOutOfMemoryError
 org.gradle.parallel=true
 org.gradle.caching=true