Upgrade to Spring Framework 6.2.6

Closes gh-1178

build.gradle

@@ -2,7 +2,7 @@ description = "Spring for GraphQL"
 
 ext {
 	moduleProjects = [project(":spring-graphql"), project(":spring-graphql-test")]
-	springFrameworkVersion = "6.2.3"
+	springFrameworkVersion = "6.2.6"
 	graphQlJavaVersion = "23.1"
 	springBootVersion = "3.4.3"
 }