fix: crypto streaming endpoint

[KisCsaj68]

Fixes issue: #784

[KisCsaj68]

To fix the issue this is a workaround I used in a docker container until this PR is merged/ released:

sed -i '' -e "s^/v1beta2/crypto^/v1beta3/crypto/us^g" $(export PYTHONUSERBASE=/usr/local;python -m site --user-site)/alpaca_trade_api/stream.py