build: Updating browserslist to 4.16.6
build: Updating browserslist to 4.16.6

* https://npmjs.com/advisories/1747 (CVE-2021-23364)

Change-Id: I546281373f615c1fbaf60451c074d429e41de717

wikimedia/mediawiki-extensions-GoogleAdSense,wikimedia/mediawiki-extensions-GoogleAdSense