build: Updating lodash to 4.17.20
build: Updating lodash to 4.17.20

* https://npmjs.com/advisories/1523
* CVE-2019-10744

Change-Id: I0e338d85e9273de42be20e1c595d49273db031d0

wikimedia/mediawiki-extensions-Arrays,wikimedia/mediawiki-extensions-Arrays