fix: update the tsconfig in the docs site to match typing in the rest of the repo

[moldy530]

Pull Request Checklist

• Did you add new tests and confirm existing tests pass? (yarn test)
• Did you update relevant docs? (docs are found in the site folder, and guidelines for updating/adding docs can be found in the contribution guide)
• Do your commits follow the Conventional Commits standard?
• Does your PR title also follow the Conventional Commits standard?
• If you have a breaking change, is it correctly reflected in your commit message? (e.g. feat!: breaking change)
• Did you run lint (yarn lint:check) and fix any issues? (yarn lint:write)
• Did you follow the contribution guidelines?

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PR-Codex overview

This PR updates dependencies, adds new packages, and adjusts configuration settings. It introduces viem, @alchemy/aa-accounts, and @alchemy/aa-alchemy packages. The TypeScript compiler options and various dependencies are also updated.

Detailed summary

• Added @alchemy/aa-accounts, @alchemy/aa-alchemy, @alchemy/aa-core, @alchemy/aa-ethers, and @alchemy/aa-signers packages
• Updated TypeScript compiler target to es2021
• Added viem package
• Updated vitepress to version 1.1.4
• Adjusted module and moduleResolution settings in tsconfig.json

The following files were skipped due to too many changes: yarn.lock

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[dphilipson]

Thank you!