Add a validate renovate config action

.github/workflows/validate-renovate-config.yml

@@ -0,0 +1,36 @@
+name: Validate renovate config
+
+on:
+    pull_request:
+        paths:
+            - renovate.json5
+        branches:
+            - main
+            - next
+    push:
+        paths:
+            - renovate.json5
+        branches:
+            - main
+            - next
+
+jobs:
+    validate:
+        name: Validate
+        runs-on: ubuntu-latest
+        steps:
+            - run: echo "${{ github.actor }}"
+
+            - uses: actions/checkout@v4
+
+            - uses: pnpm/action-setup@v4
+
+            - name: Use Node.js 22.x
+              uses: actions/setup-node@v4
+              with:
+                  node-version: 22
+                  registry-url: "https://registry.npmjs.org"
+                  cache: "pnpm" # https://github.com/actions/setup-node/blob/main/docs/advanced-usage.md#caching-packages-dependencies
+
+            - name: Validate renovate config
+              run: npx --yes --package renovate -- renovate-config-validator

renovate.json5

@@ -96,7 +96,8 @@
             // Can't upgrade because: v8 is pure ESM
             "matchPackageNames": ["query-string"], // test comment
             "matchFileNames": ["packages/**"],
-            "allowedVersions": "^7.0.0"
+            "allowedVersions": "^7.0.0",
+            "abc": "test"
         }
     ],
     "rangeStrategy": "bump",