[MAINT] Use SHA to pin GitHub actions

[ndgrigorian]

Public CI workflows have been using SHA and version pins interchangeably/at random, as workflows were added and updated sporadically, and this has become a mess

This PR addresses the technical debt by moving to SHA in all cases

Supersedes #2254

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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=0.22.0dev1=py310h93fe807_12 ran successfully.
Passed: 1244
Failed: 44
Skipped: 89

[antonwolfy]

Thank you @ndgrigorian, LGTM!

[ndgrigorian]

Thank you @ndgrigorian, LGTM!

Your kind words are appreciated, but an approval would be even better :)

[coveralls]

coverage: 86.248%. remained the same
when pulling a5f9dec on maint/use-sha-to-pin-actions
into 517fb17 on master.