deps: upgrade npm to 7.5.6

PR-URL: https://github.com/nodejs/node/pull/37496


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Beth Griggs <bgriggs@redhat.com>