deps: update dependency antsibull-docs to >=2.9,<2.10 (#474)

[![Mend
Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
|
[antsibull-docs](https://togithub.com/ansible-community/antsibull-docs)
([changelog](https://togithub.com/ansible-community/antsibull-docs/tree/main/CHANGELOG.md))
| `>=2.8,<2.9` -> `>=2.9,<2.10` |
[![age](https://developer.mend.io/api/mc/badges/age/pypi/antsibull-docs/2.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/pypi/antsibull-docs/2.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/pypi/antsibull-docs/2.8.0/2.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/antsibull-docs/2.8.0/2.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>ansible-community/antsibull-docs (antsibull-docs)</summary>

###
[`v2.9.0`](https://togithub.com/ansible-community/antsibull-docs/releases/tag/2.9.0)

[Compare
Source](https://togithub.com/ansible-community/antsibull-docs/compare/2.8.0...2.9.0)

##### Release Summary

Maintenance release.

##### Minor Changes

- Add support for the antsibull-core v3
([#&#8203;261](https://togithub.com/ansible-community/antsibull-docs/pull/261)).

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you
are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update
again.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR has been generated by [Mend
Renovate](https://www.mend.io/free-developer-tools/renovate/). View
repository job log
[here](https://developer.mend.io/github/ansible-collections/hetzner.hcloud).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzNy4yNDUuMCIsInVwZGF0ZWRJblZlciI6IjM3LjI0NS4wIiwidGFyZ2V0QnJhbmNoIjoibWFpbiJ9-->

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

requirements.txt

@@ -9,4 +9,4 @@ requests
 
 # Development requirements
 pylint
-antsibull-docs>=2.8,<2.9
+antsibull-docs>=2.9,<2.10