fix(deps): update dependency org.http4k:http4k-bom to 5.18.+

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
org.http4k:http4k-bom (source)	5.17.+ -> 5.18.+

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Release Notes

http4k/http4k (org.http4k:http4k-bom)

### [`v5.18.2.0`](https://togithub.com/http4k/http4k/blob/HEAD/CHANGELOG.md#v51820) [Compare Source](https://togithub.com/http4k/http4k/compare/5.18.1.0...5.18.2.0) - **http4k-core** : Add convenience methods to read bodies from HttpMessages as JSON/XML/CSV etc.. `request.json()` ### [`v5.18.1.0`](https://togithub.com/http4k/http4k/blob/HEAD/CHANGELOG.md#v51810) [Compare Source](https://togithub.com/http4k/http4k/compare/5.17.0.0...5.18.1.0) - **http4k-core** : Add convenience methods to set common headers to HTTP message.

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