Change function runtime node version

Thank you @Gabriele_Cimato

I would like support for SAML. It requires Node v12 or later.

console.log(JSON.stringify(process.versions))  // {"node":"10.18.1"}

const saml = require('saml');  // {}

PS: When I read documentation at https://www.mongodb.com/docs/manual/core/server-side-javascript/ I had the impression that runtime was improved at 6.0:

MongoDB 6.0 upgrades the internal JavaScript engine used for server-side JavaScript, $accumulator, $function, and $where expressions and from MozJS-60 to MozJS-91.