Start building against Spring Framework SNAPSHOTs

gradle.properties

@@ -1,7 +1,7 @@
 aspectjVersion=1.9.9.1
 springJavaformatVersion=0.0.34
 springBootVersion=2.4.2
-springFrameworkVersion=6.0.0-M6
+springFrameworkVersion=6.0.0-SNAPSHOT
 openSamlVersion=4.1.1
 version=6.0.0-SNAPSHOT
 kotlinVersion=1.7.10