New Python Program: Number Guessing Game

Hello Python enthusiasts! Let's add some fun to our repository with a classic Number Guessing Game implemented in Python. This beginner-friendly task involves creating a Python program where the computer randomly selects a number, and the user has to guess it within a limited number of attempts. This game will demonstrate basic random number generation, input handling, and conditional statements.

**Tasks:**
- Generate a random number between a specified range (e.g., 1 to 100).
- Allow the user a limited number of attempts to guess the number correctly.
- Provide feedback to the user if their guess is too high, too low, or correct.
- Display a victory message if the user guesses the number within the allowed attempts.
- Implement error handling for invalid inputs.

**Guidelines:**
- Use Python 3.x for the program.
- Ensure the game provides clear instructions and feedback to the user.
- Include comments in your code to explain the logic and functionality.
- Test the game with various scenarios to ensure it works as expected.

**Example:**

```
Welcome to the Number Guessing Game!

I'm thinking of a number between 1 and 100.
You have 7 attempts to guess it.

Enter your guess: 50
Too high! You have 6 attempts left.

Enter your guess: 30
Too low! You have 5 attempts left.

Enter your guess: 40
Correct! Congratulations, you guessed the number in 3 attempts!
```

**How to Contribute:**
1. Fork this repository.
2. Create a new Python file for the Number Guessing Game: `number_guessing_game.py`.
3. Write the Python program following the specified tasks and guidelines.
4. Test the game thoroughly to ensure it functions correctly.
5. Commit your changes: `git commit -m "Add Number Guessing Game program"`
6. Push to your branch: `git push origin add-number-guessing-game`
7. Open a pull request to this repository.

Your contribution will bring joy to users playing this classic game. Thank you for creating this entertaining Python program for our repository!