Add litellm==1.82.7 and litellm==1.82.8 to pip_blacklist and remediation
guide in security_check.py to detect compromised packages that harvest
credentials and exfiltrate via attacker-controlled server.
Also fixes two pre-existing issues in pip_blacklist scanning:
- Remove `break` that caused only the first blacklist match to be
detected, missing additional threats in multi-infection scenarios
- Replace substring matching with set-based exact matching to prevent
false positives on similar version strings (e.g. 1.82.70 vs 1.82.7)
Bump version to 4.1.
