Bump Kani version to 0.28.0

[zhassan-aws]

Description of changes:

The PR includes the candidate release notes. The following PRs were omitted from the notes:

* Update s2n-quic submodule by @zhassan-aws in https://github.com/model-checking/kani/pull/2421
* Use same perf tests for benchcomp in CI by @qinheping in https://github.com/model-checking/kani/pull/2429
* Add a new perf test by @zhassan-aws in https://github.com/model-checking/kani/pull/2422
* Remove unnecessary dependency by @celinval in https://github.com/model-checking/kani/pull/2438
* Cleanup redundant logic by @celinval in https://github.com/model-checking/kani/pull/2437

Resolved issues:

Resolves #ISSUE-NUMBER

Related RFC:

Optional #ISSUE-NUMBER.

Call-outs:

Testing:

• How is this change tested? Regressions

• Is this a refactor change? No

Checklist

• Each commit message has a non-empty body, explaining why the change was made
• Methods or procedures are documented
• Regression or unit tests are included, or existing tests cover the modified code
• My PR is restricted to a single feature or bugfix

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.