Gradle: Bump org.springdoc:springdoc-openapi-starter-webmvc-ui

Bumps [org.springdoc:springdoc-openapi-starter-webmvc-ui](https://github.com/springdoc/springdoc-openapi) from 2.8.6 to 2.8.9.
- [Release notes](https://github.com/springdoc/springdoc-openapi/releases)
- [Changelog](https://github.com/springdoc/springdoc-openapi/blob/main/CHANGELOG.md)
- [Commits](springdoc/springdoc-openapi@v2.8.6...v2.8.9)

---
updated-dependencies:
- dependency-name: org.springdoc:springdoc-openapi-starter-webmvc-ui
  dependency-version: 2.8.9
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

build.gradle.kts

@@ -164,7 +164,7 @@ val swaggerParserVersion = "2.1.31"
 val hashidsVersion = "1.0.3"
 val springOauthAutoConfigureVersion = "2.6.8"
 val springSecurityJwtVersion = "1.1.1.RELEASE"
-val springDocVersion = "2.8.6"
+val springDocVersion = "2.8.9"
 val springOauthVersion = "6.5.1"
 val servletApiVersion = "6.1.0"
 val tikaVersion = "3.1.0"