Improve docstrings in sorts/bubble_sort.py to include complexity analysis

[jgohel9902]

Feature description

The docstrings in sorts/bubble_sort.py are missing time and space complexity information, which is present in many other algorithm implementations across the repository.

Suggested improvement:
Add complexity analysis to the existing docstring:

def bubble_sort(collection: list) -> list:
"""
Bubble Sort Algorithm.

Repeatedly steps through the list, compares adjacent elements  and swaps them if they are in the wrong order.

Time Complexity:
    - Best Case: O(n) — already sorted
    - Average Case: O(n²)
    - Worst Case: O(n²)
Space Complexity: O(1) — in-place sorting

Stable: Yes

>>> bubble_sort([4, 3, 2, 1])
[1, 2, 3, 4]
"""

This would make the implementation more educational and consistent with the repository's goal of being a learning resource.