Added Type Annotations to stackapi Class Methods

[aqib-abdullahi]

This pull request enhances the code quality of the StackAPI class by adding type annotations to its methods. The added type hints improve code readability and provide better support for static type checkers and IDEs.

changes i made:

• Added type annotations to method signatures in the StackAPI class.
• Updated method parameters and return types to reflect their actual usage.
• Ensured compatibility with existing functionality and Python's type hinting system.
• Shifted some parts of the docstring of StackAPIError class from the class to constructor

Benefits:

• Improved code readability and maintainability.
• Enhanced support for static type analysis tools.
• Reduced potential for type-related bugs.

These changes do not affect the functionality of the code and no new features or bug fixes were introduced.