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

 * `custom-caddy/Dockerfile` (dockerfile)
 * `.woodpecker/build.yaml` (woodpecker)
 * `.woodpecker/pre-commit.yaml` (woodpecker)

### 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:94693a990c975907e7f13da3309b9d56ba02b3983519b41786edf5cf031e457c-->

Co-authored-by: Renovate Bot <renovate@bot.jw1.uk>
Co-authored-by: Jake Walker <hi@jakew.me>
Reviewed-on: #1
Co-authored-by: jakewbot <bot@jakew.me>
Co-committed-by: jakewbot <bot@jakew.me>

renovate.json

@@ -0,0 +1,14 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "git-submodules": {
+    "enabled": true
+  },
+  "packageRules": [
+    {
+      "matchDatasources": [
+        "git-submodules"
+      ],
+      "automerge": true
+    }
+  ]
+}