feat: support Vite v6 in mocker package

[cexbrayat]

Description

This avoids warnings like:

└─┬ vitest 3.0.0-beta.2
  └─┬ @vitest/mocker 3.0.0-beta.2
    └── ✕ unmet peer vite@^5.0.0: found 6.0.3

when using v3 beta with Vite v6 and pnpm.

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. If the feature is substantial or introduces breaking changes without a discussion, PR might be closed.
• Ideally, include a test that fails without this PR but passes with it.
• Please, don't make changes to pnpm-lock.yaml unless you introduce a new test example.

Tests

• Run the tests with pnpm test:ci.

Documentation

• If you introduce new functionality, document it. You can run documentation with pnpm run docs command.

Changesets

• Changes in changelog are generated from PR name. Please, make sure that it explains your changes in an understandable manner. Please, prefix changeset messages with feat:, fix:, perf:, docs:, or chore:.

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[sheremet-va]

Thank you!

[dubzzz]

Is there a plan to release this change within a 2.x version? (if vite 6.x is compatible with 2.x)

[sheremet-va]

Is there a plan to release this change within a 2.x version? (if vite 6.x is compatible with 2.x)

Vitest 2 will not support Vite 6, that’s the whole reason we are releasing Vitest 3