Add missing type hints to functions in searches/linear_search.py

[jgohel9902]

Feature description

Several functions in searches/linear_search.py are missing type hints on their parameters and return values, which is inconsistent with the repository's coding standards and makes the code harder to understand.

For example:
def linear_search(sequence, target):

Should be:
def linear_search(sequence: list, target: int) -> int:

Suggested improvement:

• Add type hints to all function parameters and return values
• Ensure consistency with the repo's contributing guidelines
• This would also improve IDE support and static analysis with mypy