chore: add preset validation workflow (#1)

Author: woodruffw

.github/workflows/validate.yml

@@ -0,0 +1,27 @@
+name: Validate Renovate presets
+
+on:
+  pull_request:
+    paths:
+      - "default.json"
+      - ".github/workflows/validate.yml"
+  workflow_dispatch:
+
+permissions: {}
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
+      - run: |
+          docker run --rm -v \
+            "${{ github.workspace }}:/workspace" \
+            -w /workspace \
+            ghcr.io/renovatebot/renovate:latest \
+            renovate-config-validator \
+            default.json

default.json

@@ -3,6 +3,5 @@
     "extends": [
         "config:recommended"
     ],
-    "minimumReleaseAge": "7 days",
-    "minimumReleaseAgeBehaviour": "timestamp-required"
+    "minimumReleaseAge": "7 days"
 }