NodeJS10 no longer supported by Lambda causes stack rollback

[fichmann]

Nodejs10 no longer available from Lambda runtime environments - causes the Cloudformation to stop and roll back everything.,

[fichmann]

I fixed by replacing all the references on the code from 10 to 12:
grep -e 'nodejs10' -rl . | xargs sed -i '' 's/nodejs10/nodejs12/g'

[zachelliottwx]

I've logged a PR here: #38 to fix this.