Revert "Release 6.0.0-M4"

This reverts commit 49a5f972bea8bfec601e7bd197459dd660ec7744.

docs/antora.yml

@@ -1,4 +1,4 @@
-'display_version': '6.0.0-M4'
-'name': 'ROOT'
-'prerelease': 'true'
-'version': '6.0.0-M4'
+
+name: ROOT
+version: '6.0.0'
+prerelease: '-SNAPSHOT'

gradle.properties

@@ -3,7 +3,7 @@ springJavaformatVersion=0.0.31
 springBootVersion=2.4.2
 springFrameworkVersion=6.0.0-SNAPSHOT
 openSamlVersion=3.4.6
-version=6.0.0-M4
+version=6.0.0-SNAPSHOT
 kotlinVersion=1.6.21
 samplesBranch=main
 org.gradle.jvmargs=-Xmx3g -XX:+HeapDumpOnOutOfMemoryError