fix: pin lolex to 2.7.4

Author: greenkeeper[bot]

package.json

@@ -66,7 +66,7 @@
     "jest": "^23.1.0",
     "jest-enzyme": "^6.0.1",
     "jsdom": "^11.11.0",
-    "lolex": "^2.7.0",
+    "lolex": "2.7.4",
     "pretty-bytes": "^5.1.0",
     "react": "^16.3.1",
     "react-dom": "^16.4.1",