Valid taproot signature may not must has length of 64

[timqi]

Describe the bug
It seems not right to check signature of taproot is valid by assert length of it equals 64:

btclib/btclib/psbt/psbt_utils.py

Line 307 in da0cfc1

if any(signature and len(signature) != 64 for signature in signatures):

To Reproduce
There is an example on how to make a valid taproot signature which length is not 64:
bitcoinjs/bitcoinjs-lib#1934

Environment (please complete the following information):

• OS: ubuntu
• Python version: 3.10.13
• btclib version: da0cfc1 master 2023.12.12

[timqi]

Will it support sign psbt from library?