GraphQL Java 15 Support

[setchy]

Keen to start a discussion around updating to support GraphQL Java 15.

I have these two related PRs and having io.github.graphql-java:graphql-java-annotations support graphql-java:15 is a dependency

• Updating graphql-java-servlet to use graphql-java:15 graphql-java-kickstart/graphql-java-servlet#270
• Updating graphql-spring-boot to use graphql-java:15.  graphql-java-kickstart/graphql-spring-boot#461

[setchy]

Pull Request #260

[setchy]

Merged and released - v8.2 - https://github.com/Enigmatis/graphql-java-annotations/releases/tag/v8.2

[yarinvak]

Thanks for the contribution