Suppress compiler deprecation warnings on Windows

[ndgrigorian]

This PR proposes suppressing deprecation warnings from within the compiler on Windows by marking headers as SYSTEM, similar to work done in IntelPython/dpnp#2984

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/2334/index.html

[coveralls]

coverage: 74.579%. remained the same — mark-compiler-headers-as-system into master