Update dependency com.graphql-java:graphql-java to v21

Author: renovate[bot]

gradle/libs.versions.toml

@@ -2,7 +2,7 @@
 # Libraries
 kotest = "5.6.2"
 kotest-spring = "1.1.3"
-graphql-java = "20.7"
+graphql-java = "21.3"
 graphql-kickstart-spring-boot = "15.0.0"
 commons-text = "1.10.0"
 spring-boot = "3.1.0"