feat: configure nix update and renovate pipeline (#6)

Create pipelines to run Renovate and Nix Flake lock updates.

.github/workflows/renovate.yaml

@@ -0,0 +1,16 @@
+on:
+  schedule:
+    - cron: "30 00 * * 0"
+
+jobs:
+  renovate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: checkout
+        uses: actions/checkout@v4
+      - name: Renovate
+        uses: renovatebot/github-action@v40.1.12
+        with:
+          configurationFile: renovate.json5
+          renovate-version: full
+          token: ${{ secrets.RENOVATE_TOKEN }}

.github/workflows/update-flake.yaml

@@ -0,0 +1,22 @@
+on:
+  schedule:
+    - cron: "30 00 * * 1"
+
+jobs:
+  lockfile:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Repository Checkout
+        uses: actions/checkout@v4
+
+      - name: Instal Nix
+        uses: DeterminateSystems/nix-installer-action@v1
+
+      - name: Update flake.lock
+        uses: DeterminateSystems/update-flake-lock@v22
+        with:
+          nix-options: --debug --log-format raw
+          pr-title: "deps: update flake.lock"
+          pr-labels: |
+            dependencies
+            automated

renovate.json5

@@ -0,0 +1,8 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "platform": "github",
+  "semanticCommits": true,
+  "labels": ["renovate"],
+  "repositories": ["dc-tec/k8s-gitops"],
+  "extends": ["config:recommended"],
+}