nospam extra installs packages unusable with curl_cffi #2913

The nospam extra still installs requests_cache and requests_ratelimiter (setup.py, also listed in requirements.txt), but both wrap requests-based sessions: caching sessions are rejected by YfData and rate-limiter sessions do not work with curl_cffi. So pip install yfinance[nospam] pulls in packages that cannot be used. Suggest dropping the extra, or repurposing it once a curl_cffi-compatible limiter exists.