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

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

Change-Id: If33b8b2cda29bbb87d79fa4ffb2ec6dd0f3f7d8c

wikimedia/mediawiki-extensions-Variables,wikimedia/mediawiki-extensions-Variables