Feature Request: Swap `semacode` for `dmtx`

[ksylvest]

semacode has a lot of issues installing via the native extensions with newer build tools and isn't maintained. dmtx is a strictly ruby Data Matrix generator that might be a suitable replacement.

If this repo is interested, I'd be happy to work on a PR to swap https://github.com/toretore/barby/blob/master/lib/barby/barcode/data_matrix.rb from semacode to dmtx.

[toretore]

Yes, I think that would be a good idea.

[ksylvest]

@toretore I've opened a PR here:

#120

I left a few callouts regarding needing to modify the tests, but happy to chat further if needed.

Thanks!