Add ascii_to_char conversion script (Fixes #13569)

[Vedavyasa21]

Describe your change:

• [Yes ] Add an algorithm?
• [x] Fix a bug or typo in an existing algorithm?
• [x] 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.
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• [ Yes] All functions have doctests that pass the automated testing.
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Fixes #13569

Description Added a new script ascii_to_char.py under the conversions module.
The function ascii_to_char(ascii_value: int) converts an ASCII integer to its corresponding character. Example ascii_to_char(65) 'A'

Details Added input validation for range 0–127 Included doctest for quick verification Code follows TheAlgorithms style and documentation format

[Vedavyasa21]

Can you check the changes i have made

[Vedavyasa21]

Hey! @TheAlgorithms can you check the PR.