chore(deps): pin dependency lint-staged to v6.1.1 (#879)

* chore(deps): update dependency lint-staged to v6.1.1

* Keep pinned versions + ensure `lint-staged` remains pre-7.x.

Follows-up on 17eab2d25c.

But makes sure that RenovateApp doesn't update this on our behalf.

Ref: https://renovateapp.com/docs/configuration-reference/configuration-options#allowedversions

package.json

@@ -44,7 +44,7 @@
     "husky": "0.14.3",
     "istanbul": "1.1.0-alpha.1",
     "lerna": "2.9.0",
-    "lint-staged": ">=6 < 7",
+    "lint-staged": "6.1.1",
     "mocha": "5.0.4",
     "npm-check-updates": "2.14.1",
     "prettier": "1.11.1",

renovate.json

@@ -7,5 +7,11 @@
   "rebaseStalePrs": true,
   "prCreation": "not-pending",
   "automerge": "minor",
-  "labels": ["tooling", "dependencies"]
+  "labels": ["tooling", "dependencies"],
+  "packageRules": [
+    {
+      "packageNames": ["lint-staged"],
+      "allowedVersions": "<7"
+    }
+  ]
 }