gradle-root: bump org.springdoc:springdoc-openapi-starter-webmvc-ui

Bumps [org.springdoc:springdoc-openapi-starter-webmvc-ui](https://github.com/springdoc/springdoc-openapi) from 2.6.0 to 2.8.1.
- [Release notes](https://github.com/springdoc/springdoc-openapi/releases)
- [Changelog](https://github.com/springdoc/springdoc-openapi/blob/main/CHANGELOG.md)
- [Commits](springdoc/springdoc-openapi@v2.6.0...v2.8.1)

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

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

samples/web-csr/dressca-backend/dependencies.gradle

@@ -11,7 +11,7 @@ ext {
     mybatisSpringBootStarterTestVersion = "3.0.3"
     h2Version = "2.3.232"
     postgresqlVersion = "42.7.4"
-    springdocOpenapiVersion = "2.6.0"
+    springdocOpenapiVersion = "2.8.1"
     servletApiVersion = "6.1.0"
     commonsLangVersion = "3.17.0"
     springSecurity = "3.3.4"