Zeitwerk LoadError issue with Ruby 3.1

Just spent 4 hours running down an issue. Posting it here in case other happen upon it.

The Dockerfile in Jumpstart Pro uses `ruby:3` base image which as of 2021-12-25 (two days ago) began pointing to ruby 3.1.0p0. 

Zeitwerk (latest version) can't load built-in libs like `net/smtp` and `matrix`:

```
/usr/local/bundle/gems/zeitwerk-2.5.1/lib/zeitwerk/kernel.rb:35:in `require': cannot load such file -- net/smtp (LoadError)

from /usr/local/bundle/gems/zeitwerk-2.5.1/lib/zeitwerk/kernel.rb:35:in `require'

```

To avoid the problem use `ruby:3.1` in your Dockerfile.

This may be only on Apple M1 issue. I haven't tried it on Intel.