chore: Configure Renovate (#1)

Welcome to [Renovate](https://github.com/renovatebot/renovate)! This is an onboarding PR to help you understand and configure settings before regular Pull Requests begin.

🚦 To activate Renovate, merge this Pull Request. To disable Renovate, simply close this Pull Request unmerged.

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### Detected Package Files

 * `.gitea/workflows/cd.yaml` (github-actions)
 * `.gitea/workflows/ci.yaml` (github-actions)

### What to Expect

With your current configuration, Renovate will create 1 Pull Request:

<details>
<summary>chore(deps): update actions/checkout action to v5</summary>

  - Schedule: ["at any time"]
  - Branch name: `renovate/actions-checkout-5.x`
  - Merge into: `v0`
  - Upgrade [actions/checkout](https://github.com/actions/checkout) to `v5`

</details>

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❓ Got questions? Check out Renovate's [Docs](https://docs.renovatebot.com/), particularly the Getting Started section.
If you need any further assistance then you can also [request help here](https://github.com/renovatebot/renovate/discussions).

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This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).

<!--renovate-config-hash:94693a990c975907e7f13da3309b9d56ba02b3983519b41786edf5cf031e457c-->

Reviewed-on: #1
Reviewed-by: t.behrendt <t.behrendt@noreply.localhost>
Co-authored-by: Renovate Bot <renovate@t00n.de>
Co-committed-by: Renovate Bot <renovate@t00n.de>

renovate.json

@@ -0,0 +1,3 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json"
+}