Start building against Spring Framework 6.1.0 snapshots

See gh-38312

Author: wilkinsona

gradle.properties

@@ -12,7 +12,7 @@ junitJupiterVersion=5.10.0
 kotlinVersion=1.9.20
 mavenVersion=3.9.4
 nativeBuildToolsVersion=0.9.28
-springFrameworkVersion=6.1.0-RC2
+springFrameworkVersion=6.1.0-SNAPSHOT
 tomcatVersion=10.1.15
 
 kotlin.stdlib.default.dependency=false