v6.2.1

• Avoid infinite loop when invoked without package.json
• Fall back to version in package-lock (contribution from @bschlenk in #206)
• Add tips about Docker and CI to README (contribution from @harriha in #208)
• Remove update notifier (contribution from @christianbundy in #196)
• Add github actions checks (contribution from @asadm in #186 and @DanielRuf in #188, #187)
• Fix url in README (contribution from @DanielRuf in #184)
• Upgrade node in CI to 12 (contribution from @DanielRuf in #183)