Updated peak_signal_to_noise_ratio.py

[Saswatsusmoy]

To #10563
Implemented a new function, read_image(), to read PNG images from file without OpenCV. RGB values for each pixel are stored in a nested list. Updated peak_signal_to_noise_ratio() to directly use the nested list instead of NumPy arrays. No longer relies on external libraries. Improved efficiency and independence.

• 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]

Please revert the changes to this line. Removing the type hints is NOT allowed. That would be going in the wrong direction since it would be blinding mypy which runs in our GitHub Actions.

Modifying functions that have no tests is also NOT allowed. Please create a separate pull request that adds doctests. Once that pull request is merged then we can come back to this pull request.

[cclauss]

Type hints on function parameters and doctests are mandatory.