added mean absolute percentage error

[Humzafazal72]

Describe your change:

I added mean absolute percentage error to the loss function directory. I used matrix operations instead of for loops to enhance the performance of the algorithm. Looking forward to getting this pull request merged and also to acquire the hacktoberfest and hacktoberfest-accepted badge..

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• 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.
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[algorithms-keeper]

Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

• Contributing guidelines
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Python:

• Formatted string literals (f-strings)
• Type hints
• doctest
• unittest
• pytest

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[algorithms-keeper]

As there is no test file in this pull request nor any test function or class in the file machine_learning/loss_functions/mean_absolute_percentage_error.py, please provide doctest for the function mean_absolute_percentage_error

[tianyizheng02]

All loss function files were consolidated into machine_learning/loss_functions.py in #10737. Could you move your new code into that file?

[Humzafazal72]

All loss function files were consolidated into machine_learning/loss_functions.py in #10737. Could you move your new code into that file?
I have added my code into loss_functions.py.

[tianyizheng02]

Could you move your function to the bottom of the file, right below mean_squared_logarithmic_error?

[Humzafazal72]

Could you move your function to the bottom of the file, right below mean_squared_logarithmic_error?

Done as requested.