chore: migrate AWS SDK for JavaScript v2 APIs to v3

[trivikr]

Description

From AWS SDK for JavaScript v2 README:

We are formalizing our plans to make the Maintenance Announcement (Phase 2) for AWS SDK for JavaScript v2 in 2023.

This PR migrates AWS SDK for JavaScript v2 APIs to v3 using aws-sdk-js-codemod.

$ npx aws-sdk-js-codemod@0.28.2 -t v2-to-v3 packages/sign-client/**/*.ts

Type of change

• Chore (non-breaking change that addresses non-functional tasks, maintenance, or code quality improvements)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Draft PR (breaking/non-breaking change which needs more work for having a proper functionality [Mark this PR as ready to review only when completely ready])
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How has this been tested?

N/A

Checklist

• I have performed a self-review of my own code
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[bkrem]

LGTM, thank you for upgrading this @trivikr 🙏

Tagging @arein and @ganchoradkov as the folks most familiar with the touched code and the pipeline. Looks like a types-only kind of change though anyways 👍

[ganchoradkov]

thank you for the PR @trivikr 💯