Preload weights

[servantftransperfect]

Hello,

First of all thanks for this amazing work.

In Roma V1, it was possible to pass weights to the main matching function.
In Roma V2, it forces the load from the web.

Would it be possible to enable load of weights from a local file ? Do you need me to write a PR ?

Thanks,

Fabien

[Parskatt]

Sure, please send in a PR for review and I'll have a look :)