Bump org.jetbrains.kotlinx:kotlinx-serialization-json

Bumps [org.jetbrains.kotlinx:kotlinx-serialization-json](https://github.com/Kotlin/kotlinx.serialization) from 1.7.+ to 1.8.0.
- [Release notes](https://github.com/Kotlin/kotlinx.serialization/releases)
- [Changelog](https://github.com/Kotlin/kotlinx.serialization/blob/master/CHANGELOG.md)
- [Commits](https://github.com/Kotlin/kotlinx.serialization/commits/v1.8.0)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlinx:kotlinx-serialization-json
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

graphql-dgs-codegen-core/build.gradle

@@ -38,7 +38,7 @@ dependencies {
     implementation 'com.squareup:kotlinpoet:1.17.+'
     implementation 'com.github.ajalt.clikt:clikt:4.4.+'
 
-    implementation 'org.jetbrains.kotlinx:kotlinx-serialization-json:1.7.+'
+    implementation 'org.jetbrains.kotlinx:kotlinx-serialization-json:1.8.+'
     implementation 'jakarta.annotation:jakarta.annotation-api:3.0.+'