Use BigInt and datatables>=1.13 rather than converting large integers to str

[mwouts]

This is a follow-up on #152 . Large Python integers cannot be represented as native JavaScript integers. From itables==1.5.2 we therefore convert them to str, but because of that they might not be sorted properly in datatables.

A more correct workaround would be

• to encode the large integers using BigInt (however this does not seem to be supported by json.dumps at the moment?)
• to use datatables>=1.13 which has support for these BigInt (however datatables>=1.13 requires import maps, which is a significant change, and will require modern browsers)