housekeeping(dev-deps): deepmerge v4 (#6098)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

package-lock.json

@@ -7827,9 +7827,9 @@
       "dev": true
     },
     "deepmerge": {
-      "version": "2.2.1",
-      "resolved": "https://registry.npmjs.org/deepmerge/-/deepmerge-2.2.1.tgz",
-      "integrity": "sha512-R9hc1Xa/NOBi9WRVUWg19rl1UB7Tt4kuPd+thNJgFZoxXsTz7ncaPaeIm+40oSGuP33DfMb4sZt1QIGiJzC4EA==",
+      "version": "4.2.2",
+      "resolved": "https://registry.npmjs.org/deepmerge/-/deepmerge-4.2.2.tgz",
+      "integrity": "sha512-FJ3UgI4gIl+PHZm53knsuSFpE+nESMr7M4v9QcgB7S63Kj/6WqMiFQJpBBYz1Pt+66bZpP3Q7Lye0Oo9MPKEdg==",
       "dev": true
     },
     "default-gateway": {

package.json

@@ -111,7 +111,7 @@
     "css-loader": "^3.5.3",
     "cypress": "^3.8.3",
     "dedent": "^0.7.0",
-    "deepmerge": "^2.1.0",
+    "deepmerge": "^4.0.0",
     "enzyme": "^2.7.1",
     "eslint": "^4.1.1",
     "eslint-plugin-import": "^2.20.2",