CHANGELOG: Update release date for v3.5.16

[ivanvc]

Updated 3.5 CHANGELOG to reflect today's release.

Part of #18485.

Please read https://github.com/etcd-io/etcd/blob/main/CONTRIBUTING.md#contribution-flow.

[jmhbnz]

LGTM - Thanks @ivanvc

[k8s-ci-robot]

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This pull-request has been approved by: ivanvc, jmhbnz

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.83%. Comparing base (4997a2b) to head (843db04).

❗ Current head 843db04 differs from pull request most recent head 96e17d3

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Additional details and impacted files

see 14 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #18573      +/-   ##
==========================================
- Coverage   68.89%   68.83%   -0.06%     
==========================================
  Files         420      420              
  Lines       35474    35474              
==========================================
- Hits        24439    24420      -19     
- Misses       9621     9635      +14     
- Partials     1414     1419       +5     

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[ivanvc]

/retest

[k8s-ci-robot]

@ivanvc: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-etcd-govulncheck	96e17d3	link	true	/test pull-etcd-govulncheck

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[ivanvc]

Expected failure. Refer to: #18548 (comment)