chore: remove coinbasepro exchange

ccxt removed this exchange in ccxt/ccxt#22502.

Author: xmatthias

freqtrade/exchange/__init__.py

@@ -10,7 +10,6 @@
 from freqtrade.exchange.bitpanda import Bitpanda
 from freqtrade.exchange.bitvavo import Bitvavo
 from freqtrade.exchange.bybit import Bybit
-from freqtrade.exchange.coinbasepro import Coinbasepro
 from freqtrade.exchange.cryptocom import Cryptocom
 from freqtrade.exchange.exchange_utils import (
     ROUND_DOWN,