Add weather check function

[Hbeyza]

This pull request introduces a function to handle different weather conditions based on user input. The function provides appropriate responses for common weather types (sunny, rainy, snowy, cloudy) and handles unexpected inputs gracefully.

Changes:

• Added check_weather function to provide weather-related messages.
• Added ask_weather function to take user input and call check_weather.
• Added main function to initiate the weather checking process.

The function is case-insensitive and responds correctly to known and unknown weather conditions.

Example outputs:

• Input: "sunny" → Output: "It's bright today!"
• Input: "rainy" → Output: "Take an umbrella."
• Input: "windy" → Output: "I don't know this weather."