Add algorithm for approximating the nth root with Newton's Method

[CarlosZamG]

Describe your change:

Similar to maths/numerical_analysis/square_root.py, the new file contains a function that approximates the nth root of a real number using Newton's method.

See: https://en.wikipedia.org/wiki/Nth_root#Using_Newton's_method

• Add an algorithm?
• 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:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• 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 #ISSUE-NUMBER".

[cclauss]

pre-commit.ci run

[priya-sundaram-dev]

Reviewed in the oldest-PR triage sweep. The algorithm and documentation here are excellent (clear derivation, references, and doctests covering negative radicands, domain errors, and a convergence check).

The blocker is the ruff failure: from math import pow shadows the builtin (A004) and is flagged. Since you only use it as a power operation, the simplest fix is to drop the import and use the ** operator (e.g. x_k ** (index - 1)), or import math and call math.pow(...) fully-qualified. After that ruff should pass and this is merge-ready.