Add Renovate github actions workflow

Author: smokestacklightnin

.github/workflows/renovate.yml

@@ -0,0 +1,19 @@
+name: Renovate
+on:
+  workflow_dispatch:
+  schedule:
+    # The "*" (#42, asterisk) character has special semantics in YAML, so this
+    # string has to be quoted.
+    - cron: '0/5 * * * *'
+jobs:
+  renovate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/[email protected]
+      - name: Self-hosted Renovate
+        uses: renovatebot/[email protected]
+        with:
+          token: ${{ secrets.RENOVATE_TOKEN }}
+        env:
+          RENOVATE_REPOSITORIES: "smokestacklightnin/nebari"