Add inflect dependency for DiffRhythm2 g2p module

Fixes ModuleNotFoundError: No module named 'inflect'
Required by g2p/g2p/english.py for English number-to-word conversion

requirements.txt

@@ -28,6 +28,7 @@ pykakasi>=2.3.0,<3.0.0  # Japanese text processing
 pyopenjtalk>=0.3.0,<0.5.0; python_version < "3.12"  # Japanese phonetics (Python 3.11 compatible)
 unidecode>=1.3.0,<2.0.0  # Text normalization
 py3langid>=0.2.2,<0.4.0  # Language detection
+inflect>=5.0.0,<8.0.0  # English number-to-word conversion for g2p
 
 # AI Model dependencies - tightly constrained for compatibility
 transformers==4.47.1  # Pinned for DiffRhythm2 compatibility