Internal TypeVar on Field is Overly Strict

[Alex Rothberg]

The Internal TypeVar on Fields should probably allow Any types rather than just the list of supported External values

shillelagh/src/shillelagh/fields.py

Lines 12 to 23 in 97197bd

 Internal = TypeVar( 
     "Internal", 
     float, 
     int, 
     str, 
     bool, 
     datetime.date, 
     datetime.datetime, 
     datetime.time, 
     datetime.timedelta, 
     bytes, 
 ) 

i.e. this corresponds to what the API returns which can be broader than the list offered. For example, APIs might use Lists or even Dicts to represent (scalar) values.