Fix the separator issue

[osman-haider]

Describe your change:

This pull request fixes a bug in the existing split.py algorithm. The original implementation did not correctly handle strings that end with the separator, resulting in a missing empty string in the output array compared to the expected behavior of Python's built-in str.split() method. The update corrects this discrepancy, ensuring that the custom split function now accurately mimics the behavior of str.split() by including trailing empty strings when the input string ends with the separator.

• [Yes] Add an algorithm?
• [Yes] Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

Checklist:

• [Yes ] I have read CONTRIBUTING.md.
• [Yes ] This pull request is all my own work -- I have not plagiarized.
• [Yes ] I know that pull requests will not be merged if they fail the automated tests.
• [Yes] This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• [Yes] All new Python files are placed inside an existing directory.
• [Yes] All filenames are in all lowercase characters with no spaces or dashes.
• [Yes] All functions and variable names follow Python naming conventions.
• [Yes] All function parameters and return values are annotated with Python type hints.
• [Yes] All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes strings/split.py is incorrect #12403".