deps: upgrade npm to 7.15.0

v7.15.0 (2021-05-27)

FEATURES

• 399ff8cbc #3312 feat(link): add workspace support (@isaacs)

BUG FIXES

• 46a9bcbcb #3282 fix(docs): proper postinstall script file name (@KevinFCormier)
• 83590d40f #3272 fix(ls): show relative paths from root (@isaacs)
• a574b518a #3304 fix(completion): restore IFS even if npm completion returns error (@NariyasuHeseri)
• 554e8a5cd #3311 set audit exit code properly (@isaacs)
• 4a4fbe33c #3268 #3285 fix(publish): skip private workspaces (@ruyadorno)

DOCUMENTATION

• 3c53d631f #3307 fix(docs): typo in package-lock.json docs (@rethab)
• 96367f93f rebuild npm-pack doc (@isaacs)
• 64b13dd10 #3313 Drop stale Python 3<->node-gyp remark (@spencerwilson)

DEPENDENCIES

• 7b56bfdf3 cacache@15.2.0:
  • feat: allow fully deleting indices
  • feat: add a validateEntry option to compact
  • chore: lint
  • chore: use standard npm style release scripts
• dbbc151a3 npm-audit-report@2.1.5:
  • fix(exit-code): account for null auditLevel default (#46 (closed))
• 5b2604507 chore(package-lock): update devDependencies (@Gar)

AUTOMATION

• 3d5df0082 #3294 chore(ci): move node release PR workflow to cli repo (@gimli01)