Bump io.confluent:kafka-json-schema-serializer from 7.6.0 to 7.8.0

Bumps [io.confluent:kafka-json-schema-serializer](https://github.com/confluentinc/schema-registry) from 7.6.0 to 7.8.0.
- [Commits](confluentinc/schema-registry@v7.6.0...v7.8.0)

---
updated-dependencies:
- dependency-name: io.confluent:kafka-json-schema-serializer
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

data-prepper-plugins/kafka-plugins/build.gradle

@@ -39,7 +39,7 @@ dependencies {
     implementation 'io.micrometer:micrometer-core'
     implementation libs.commons.lang3
     implementation 'io.confluent:kafka-avro-serializer:7.6.0'
-    implementation 'io.confluent:kafka-json-schema-serializer:7.6.0'
+    implementation 'io.confluent:kafka-json-schema-serializer:7.8.0'
     implementation 'io.confluent:kafka-schema-registry-client:7.6.0'
     implementation 'software.amazon.awssdk:sts'
     implementation 'software.amazon.awssdk:auth'