Configured Renovate (#10672)

no issue

- Added default config
- Silently automerge test & lint deps
- Added validator to ignoreDeps
- ^ Because we monkeypatch validator prototype with 'extend' method and updating it should be handled more carefully as a separate task. Ref -  https://github.com/TryGhost/Ghost/blob/be27db4/core/server/data/validation/index.js#L55

renovate.json

@@ -0,0 +1,22 @@
+{
+  "extends": [
+    "@tryghost:base",
+    "@tryghost:groupTestLint",
+    "@tryghost:groupCSS",
+    "@tryghost:groupBuildTools",
+    "@tryghost:automergeSilentTestLintNonMajor"
+  ],
+  "travis": { "enabled": true },
+  "node": {
+    "supportPolicy": ["lts"]
+   },
+  "separateMinorPatch": true,
+  "patch": {
+    "automerge": true
+  },
+  "ignoreDeps": [
+      "nodemailer",
+      "validator"
+    ],
+  "ignorePaths": ["core/test"]
+}