Drop support python 3.9

[antonwolfy]

The PR drop support of python 3.10 and sets python 3.10 as a minimum required.

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpnp/pull/2626/index.html

[github-actions]

Array API standard conformance tests for dpnp=0.20.0dev0=py313h509198e_11 ran successfully.
Passed: 1227
Failed: 0
Skipped: 9

[coveralls]

coverage: 67.791%. remained the same
when pulling 4232136 on drop-python-3.9
into fc14877 on master.