ci: add action that updates dependencies every 6 months

Author: leahaeusel

.github/renovate.json

@@ -0,0 +1,17 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "config:base"
+  ],
+  "packageRules": [
+    {
+      "matchManagers": ["pip", "conda"],
+      "groupName": "Python dependencies"
+    },
+    {
+      "matchManagers": ["github-actions"],
+      "groupName": "GitHub actions"
+    }
+  ],
+  "dependencyDashboard": true
+}

.github/workflows/update_dependencies.yml

@@ -0,0 +1,19 @@
+name: update_dependencies
+on:
+    schedule:
+        - cron: "0 0 1 2 *" # 1st of February at 00:00 UTC
+        - cron: "0 0 1 8 *" # 1st of August at 00:00 UTC
+    push: # TODO: remove later, only for testing
+jobs:
+    run_renovate:
+        runs-on: ubuntu-latest
+        steps:
+            - name: Checkout
+              uses: actions/checkout@v6.0.2
+            - name: Run self-hosted Renovate
+              uses: renovatebot/github-action@v44.2.5
+              with:
+                  repositories: "queens-py/queens"
+                  token: ${{ secrets.RENOVATE_TOKEN }}
+              env:
+                  RENOVATE_REPOSITORIES: "queens-py/queens"