Update handlebars dependency to ^4.1.2

[juliusl]

Handlebars has a security advisory out for 4.1.1, so yarn/npm audit will complain about ^4.1.0. This is to fix that.

[juliusl]

Temporary workaround for yarn users is to add to package.json

"resolutions": {
  "handlebars": "^4.1.2"
}

For npm users npm audit fix will work.

[parkerziegler]

Thanks @juliusl! Do you mind re-running yarn install with this change applied in your local brach? We want to make sure that changes to the yarn.lock file also make their way into source (your PR only updates the package.json currently 😄).

[juliusl]

@parkerziegler Sure no problem, pushed new yarn.lock.

[parkerziegler]

Thanks!