deps: upgrade npm to 6.14.1

Backport-PR-URL: https://github.com/nodejs/node/pull/32527
PR-URL: https://github.com/nodejs/node/pull/31977


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>