Add renovate (#24)

Co-authored-by: Henrique Santos <henrique.santos@freiheit.com>

.github/renovate.json

@@ -0,0 +1,20 @@
+{
+    "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+    "extends": [
+        "config:recommended"
+    ],
+    "prHourlyLimit": 10,
+    "labels": [
+        "renovate"
+    ],
+    "repositories": [
+        "stackitcloud/terraform-provider-stackit"
+    ],
+    "enabledManagers": [
+        "gomod",
+        "github-actions"
+    ],
+    "postUpgradeOptions": [
+        "gomodTidy"
+    ]
+}

.github/workflows/renovate.yaml

@@ -0,0 +1,19 @@
+name: Renovate
+
+on:
+  schedule:
+    - cron: '0 0 * * *'
+  workflow_dispatch:
+
+jobs:
+  renovate:
+    name: Renovate
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Self-hosted Renovate
+        uses: renovatebot/github-action@v39.0.5
+        with:
+          configurationFile: .github/renovate.json
+          token: ${{ secrets.RENOVATE_TOKEN }}