chore(deps): bump org.http4k:http4k-server-undertow (#931)

Bumps [org.http4k:http4k-server-undertow](https://github.com/http4k/http4k) from 5.13.2.0 to 5.13.6.1.
- [Release notes](https://github.com/http4k/http4k/releases)
- [Changelog](https://github.com/http4k/http4k/blob/master/CHANGELOG.md)
- [Commits](http4k/http4k@5.13.2.0...5.13.6.1)

---
updated-dependencies:
- dependency-name: org.http4k:http4k-server-undertow
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

run/http4k-hello-world/build.gradle.kts

@@ -9,7 +9,7 @@ repositories {
 
 dependencies {
     implementation("org.http4k:http4k-core:5.13.2.0")
-    implementation("org.http4k:http4k-server-undertow:5.13.2.0")
+    implementation("org.http4k:http4k-server-undertow:5.13.6.1")
 }
 
 kotlin {