Add dpnp.ndarray.__bytes__ method

[antonwolfy]

The PR implements a special python method __bytes__ for dpnp.ndarray.

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[github-actions]

Array API standard conformance tests for dpnp=0.20.0dev0=py313h509198e_57 ran successfully.
Passed: 1229
Failed: 0
Skipped: 7

[github-actions]

View rendered docs @ https://intelpython.github.io/dpnp/index.html

[coveralls]

coverage: 81.455% (+0.002%) from 81.453%
when pulling 3e67df0 on add-bytes-method-impl
into 0c92fce on master.

[vlad-perevezentsev]

LGTM
Thank you @antonwolfy