fix: use adjoint matrix for 3x3 inverse

[abhi-zit77]

Describe your change:

Fixes the 3x3 branch of inverse_of_matrix() so it uses the computed adjoint matrix when applying the inverse formula. Previously, the function computed adjoint_matrix but seeded inverse_matrix from cofactor_matrix, returning the transpose of the true inverse for non-symmetric 3x3 matrices.

Fixes #14813

How tested

• .\.venv\Scripts\python.exe -m doctest -v matrix\inverse_of_matrix.py
• .\.venv\Scripts\python.exe -m pytest --doctest-modules matrix\inverse_of_matrix.py -q
• .\.venv\Scripts\ruff.exe check matrix\inverse_of_matrix.py
• .\.venv\Scripts\python.exe -m mypy --ignore-missing-imports matrix\inverse_of_matrix.py
• git diff --check

• 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.
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• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
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