Pydantic V1 support

[maxschulz-COL]

Is your feature request related to a problem? Please describe. First of all, I love this library, it's just SO cool!!

I would love to implement it in conjunction with the OS library I am helping to develop (https://github.com/mckinsey/vizro), which still uses Pydantic V1 for the near future...

Describe the solution you'd like Instructor also work with Pydantic V1 base models

Describe alternatives you've considered We should upgrade to V2, and eventually we will :) Just cannot do it just yet

I didn't check the source code on whether this is a crazy effort or even feasible, but thought I'd better ask :)!