Update lodash to version 4.17.20 (#1)

Co-authored-by: depfu[bot] <23717796+depfu[bot]@users.noreply.github.com>

Author: depfu[bot]

package-lock.json

@@ -71,7 +71,7 @@
     "karma-sourcemap-loader": "0.3.7",
     "karma-spec-reporter": "0.0.26",
     "karma-webpack": "1.8.0",
-    "lodash": "^4.17.15",
+    "lodash": "^4.17.20",
     "lolex": "1.5.2",
     "mocha": "2.5.3",
     "mocha-generators": "1.2.0",