Python3 migration

[KoikyLansoy]

Migration from Python 2.7 to Python 3

Summary

This PR migrates the AnalyzePDF script from Python 2.7 to Python 3, ensuring compatibility with modern Python environments while keeping existing functionality unchanged.

🧪 Testing

• [x] Script compiles without syntax errors
• [x] YARA rules compile successfully
• [x] All print statements display properly
• [x] Tested with : classic pdf, multiple filtering, invalid_xref_numbers as I changed the regex

🔍 Changes

• None - All functionality preserved
• Script now requires Python 3.x instead of Python 2.7
• YARA library dependency updated to yara-python in doc