Upgrade to Spring Framework 6.0.18

Closes gh-938

build.gradle

@@ -2,7 +2,7 @@ description = "Spring for GraphQL"
 
 ext {
 	moduleProjects = [project(":spring-graphql"), project(":spring-graphql-test")]
-	springFrameworkVersion = "6.0.17"
+	springFrameworkVersion = "6.0.18"
 	graphQlJavaVersion = "20.9"
 	springBootVersion = "3.1.5"
 }
@@ -39,7 +39,7 @@ configure(moduleProjects) {
 	}
 
 	configurations {
-		dependencyManagement {
+		dependencyManagement {6
 			canBeConsumed = false
 			canBeResolved = false
 			visible = false
@@ -54,7 +54,7 @@ configure(moduleProjects) {
 	ext.javadocLinks = [
 			"https://docs.oracle.com/en/java/javase/17/docs/api/",
 			"https://docs.spring.io/spring-framework/docs/6.0.x/javadoc-api/",
-			"https://javadoc.io/doc/com.graphql-java/graphql-java/20.7/"
+			"https://javadoc.io/doc/com.graphql-java/graphql-java/${graphQlJavaVersion}/"
 	] as String[]
 
 	components.java.withVariantsFromConfiguration(configurations.testFixturesApiElements) { skip() }