Add pytest for heap_sort

[NavanithaSri]

• I have read the contribution guidelines
• My code follows PEP8 style
• Added pytest or doctest
• My code is tested
• Other points not relevant left unchecked

[cclauss]

@priya-sundaram-dev I merged this one because it would be good to start following the Python convention of having a tests/ directory. We can use if for pytests that cover similar algorithms like a parameterized tests. For all algorithms in the sorts directory, sort([10, -10, -1, 1, 0]), sort([1.1, -1.1, -1, 1, 0]), sort("Python!").

[priya-sundaram-dev]

Love it — a tests/ directory with parameterized tests is the right call. I ran with your three examples in #15185: a single test_sort_matches_builtin runs 20 general-purpose sorts × 9 inputs (your negatives / floats / "Python!" string, plus empty, single, duplicate-heavy, sorted, and reverse-sorted), all green, with the original test_heap_sort kept intact.

Two real bugs fell out while I was at it (kept out of the green suite so CI stays honest — can fix in separate PRs on your word):

• tim_sort([]) → IndexError
• tree_sort([3,3,1,2,2,1]) → [1,2,3] (drops duplicates)

The module docstring documents why the domain-restricted sorts (counting_sort, radix_sort, bead_sort, dutch_national_flag_sort, bitonic_sort, topological_sort, …) are excluded rather than silently skipped.

_{🤖 #ABotWroteThis}