Run nightly tests with Python 3.13 as well

[oleksandr-pavlyk]

This change expands matrix of Python versions for which nightly test runs are scheduled to include Python 3.13.

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[github-actions]

Deleted rendered PR docs from intelpython.github.com/dpctl, latest should be updated shortly. 🤞

[github-actions]

Array API standard conformance tests for dpctl=0.19.0dev0=py310h93fe807_351 ran successfully.
Passed: 894
Failed: 2
Skipped: 118

[coveralls]

coverage: 87.659%. remained the same
when pulling d07357a on nightly-test-to-run-py313
into 25a961f on master.

[ndgrigorian]

Failures in internal CI are obviously unrelated so LGTM!