Fix deprecation: Test framework implementation dependencies (Gradle 9.0) #36

Issue

The automatic loading of test framework implementation dependencies has been deprecated and will be removed in Gradle 9.0.

Warning Message

The automatic loading of test framework implementation dependencies has been deprecated. 
This is scheduled to be removed in Gradle 9.0. Declare the desired test framework directly 
on the test suite or explicitly declare the test framework implementation dependencies on 
the test's runtime classpath.

Affected Project

Root library (graphql-java-codegen)

Fix Required

Explicitly declare the test framework implementation dependencies in build.gradle:

dependencies {
    testImplementation "org.junit.jupiter:junit-jupiter-api:5.10.2"
    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:5.10.2"
}

Or migrate to the JVM Test Suite Plugin for better test framework configuration.

References

• https://docs.gradle.org/8.14.3/userguide/upgrading_version_8.html#test_framework_implementation_dependencies
• Removal version: Gradle 9.0