[release/6.x] Bump Swashbuckle.AspNetCore.SwaggerGen (#7528)

Bumps [Swashbuckle.AspNetCore.SwaggerGen](https://github.com/domaindrivendev/Swashbuckle.AspNetCore) from 6.8.1 to 6.9.0.
- [Release notes](https://github.com/domaindrivendev/Swashbuckle.AspNetCore/releases)
- [Commits](domaindrivendev/Swashbuckle.AspNetCore@v6.8.1...v6.9.0)

---
updated-dependencies:
- dependency-name: Swashbuckle.AspNetCore.SwaggerGen
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

eng/dependabot/independent/Versions.props

@@ -20,6 +20,6 @@
     <!-- Third-party references -->
     <NewtonsoftJsonVersion>13.0.3</NewtonsoftJsonVersion>
     <NJsonSchemaVersion>11.0.0</NJsonSchemaVersion>
-    <SwashbuckleAspNetCoreSwaggerGenVersion>6.8.1</SwashbuckleAspNetCoreSwaggerGenVersion>
+    <SwashbuckleAspNetCoreSwaggerGenVersion>6.9.0</SwashbuckleAspNetCoreSwaggerGenVersion>
   </PropertyGroup>
 </Project>