Bump org.openapi.generator from 7.7.0 to 7.8.0

Bumps org.openapi.generator from 7.7.0 to 7.8.0.

---
updated-dependencies:
- dependency-name: org.openapi.generator
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

contract/build.gradle

@@ -23,7 +23,7 @@ import org.apache.avro.Conversions
 plugins {
     id "java"
     id "idea"
-    id "org.openapi.generator" version "7.7.0"
+    id "org.openapi.generator" version "7.8.0"
     id "com.github.davidmc24.gradle.plugin.avro" version "1.9.1"
     id 'com.google.protobuf' version '0.9.4'
 }