Add configurable max workers for concurrent requests

[dhruv1955]

Summary

Adds a configurable --max-workers argument to let users control the number of concurrent workers for social media requests.

Problem

The current hardcoded limit of 20 workers restricts users from optimizing performance and scalability.

Solution

• Added --max-workers argument (range: 1–100) with validation
• Introduced max_workers_check() for input validation
• Updated sherlock() to accept the parameter
• Preserved default behavior for backward compatibility

Testing

• ✅ Input validation for edge cases (0, negative, >100)
• ✅ Integrated with argument parser
• ✅ Maintains default behavior when unspecified
• ✅ No breaking changes

Benefits

• Enables performance tuning
• Prevents excessive concurrency
• Resolves TODO about hardcoded limits
• Improves flexibility and maintainability