Docstring of expand_dims to reflect that axis can be a tuple

[oleksandr-pavlyk]

tensor.expand_dims docstring change only.

Documentation string now reflects that axis keyword argument is allowed to be a tuple of integers.

See data-apis/array-api#760

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[github-actions]

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

[coveralls]

coverage: 87.743%. remained the same
when pulling bfec575 on expand-dims-docstring
into 13f4443 on master.

[github-actions]

Array API standard conformance tests for dpctl=0.17.0dev0=py310h15de555_74 ran successfully.
Passed: 906
Failed: 0
Skipped: 94

[ndgrigorian]

LGTM!