[Snyk] Security upgrade blockstack from 18.1.0 to 21.0.0#10

Open

snyk-bot wants to merge 1 commit intodevelopfrom snyk-fix-f97ccfb4a2c53bbd2d6b5c175a722f0d

+283-230

Commits on Sep 12, 2020

fix: package.json & package-lock.json to reduce vulnerabilities
snyk-bot
committed