Updated config.py

Database upgrade & pattern fixes:

- Lowercased all 5 pattern lists (GREETING_PATTERNS, FAREWELL_PATTERNS, GRATITUDE_PATTERNS, CONFUSION_PATTERNS, UNCERTAIN_RESPONSES) for case-insensitive matching

- Removed duplicate 'nahh' from NO_RESPONSES
- Added 'later' to COMMON_SHORT_WORDS to prevent false topic triggers

- Added 'don't teach me' variants to NO_RESPONSES
- Strengthened 'teach me' detection in YES_RESPONSES with variants (teach me bro, teach me man, teach me master)

- Added 35 common words to COMMON_SHORT_WORDS
- Added 'what did you said' variants to last_response_pattern

Author: acubura