proxy: enable sha2 asm support

[conradludgate]

Problem

faster sha2 hashing.

Summary of changes

enable asm feature for sha2. this feature will be default in sha2 0.11, so we might as well lean into it now. It provides a noticeable speed boost on macos aarch64. Haven't tested on x86 though

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

2706 tests run: 2575 passed, 0 failed, 131 skipped (full report)

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Code coverage* (full report)

• functions: 28.3% (7131 of 25197 functions)
• lines: 46.9% (43717 of 93289 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
9110c5b at 2024-03-20T11:40:54.603Z :recycle:}

[stradig]

LGTM