Configure Renovate (#2)

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/deploy.yml` (github-actions)
 * `go.mod` (gomod)

### What to Expect

It looks like your repository dependencies are already up-to-date and no Pull Requests will be necessary right away.

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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:1fced96aededec54a3f23c6f3f1084b8235cf80807dcd53bdeba6dda8cbeb623-->

Reviewed-on: #2
Co-authored-by: Renovate Bot <renovate-bot@git.cantorgymnasium.de>
Co-committed-by: Renovate Bot <renovate-bot@git.cantorgymnasium.de>

renovate.json

@@ -0,0 +1,6 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "local>gcg/renovate-config"
+  ]
+}