Change samplesBranch property to point to correct branch

Closes gh-11040

gradle.properties

@@ -5,7 +5,7 @@ springFrameworkVersion=6.0.0-M2
 openSamlVersion=3.4.6
 version=6.0.0-SNAPSHOT
 kotlinVersion=1.6.20-M1
-samplesBranch=6.0.x
+samplesBranch=main
 org.gradle.jvmargs=-Xmx3g -XX:+HeapDumpOnOutOfMemoryError
 org.gradle.parallel=true
 org.gradle.caching=true