v3.0.0

Updated for PHP 8.1 and modern PSR log support.

• PHP minimum version 8.1.
• Requires psr/log ^3.0 (dropped 2.0 support).
• setOutput() renamed to setStdout() for clarity.
• Improved log file locking.
• Input sanitization.
• Uses Psr\Log\InvalidArgumentException for invalid log levels.