Update dependency org.http4k:http4k-bom to v6.20.0.0 (#286)

| datasource | package               | from     | to       |
| ---------- | --------------------- | -------- | -------- |
| maven      | org.http4k:http4k-bom | 6.19.0.0 | 6.20.0.0 |

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

libs.versions.toml

@@ -2,7 +2,7 @@
 jdk = "21"
 kotlin = "2.2.20"
 moshix = "0.32.0"
-http4k = "6.19.0.0"
+http4k = "6.20.0.0"
 immutables = "2.11.6"
 arrow = "2.1.2"
 graal = "25.0.1"