Bump org.openapi.generator from 7.7.0 to 7.20.0

Bumps org.openapi.generator from 7.7.0 to 7.20.0.

---
updated-dependencies:
- dependency-name: org.openapi.generator
  dependency-version: 7.20.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -56,7 +56,7 @@ cyclonedxVersion = "1.8.2"
 dokkaVersion = "1.9.10"
 testLoggerVersion = "4.0.0"
 sonarVersion = "5.1.0.4882"
-openApiGeneratorVersion = "7.7.0"
+openApiGeneratorVersion = "7.20.0"
 
 [libraries]
 apache-commons-codec = { group = "commons-codec", name = "commons-codec", version.ref = "apacheCommonsCodecVersion" }