Bump Vitest version to ^1.4.0

[tjprescott]

See: vitest-dev/vscode#257

To resolve the issue on my machine (Windows) I need to use the pre-release version of the vitest.dev extension. Not sure if there's a way to recommend it in .vscode/extensions.json but regardless, the vitest version needs to be bumped to support using it.

Did confirm that this pretty much resolves the issues I was having running tests.

[azure-sdk]

❌ There is undocummented changes. Run chronus add to add a changeset or click here.

The following packages have changes but are not documented.

• ❌@typespec/bundler
• ❌@typespec/compiler
• ❌@typespec/eslint-plugin
• ❌@typespec/html-program-viewer
• ❌@typespec/http
• ❌@typespec/internal-build-utils
• ❌@typespec/json-schema
• ❌@typespec/library-linter
• ❌@typespec/openapi
• ❌@typespec/openapi3
• ❌@typespec/prettier-plugin-typespec
• ❌@typespec/protobuf
• ❌@typespec/rest
• ❌typespec-vscode
• ❌@typespec/versioning

[timotheeguerin]

@tjprescott I am bumping all dependencies here already including vitest to 1.4.0 #3027

[azure-sdk]

You can try these changes at https://cadlplayground.z22.web.core.windows.net/prs/3028/

Check the website changes at https://tspwebsitepr.z22.web.core.windows.net/prs/3028/

[tjprescott]

Closing in favor of #3027