fix(tests): fix tests run fail in the Chinese directory

[ygj6]

Description

in #3582 ，

when vite's workspace contains Chinese directory，vite tests run fails in Windows

it is caused by the slash component vite use to convert Windows backslash paths to slash paths

e.g the path foo/bar in Unix will be slashed to be foo\\bar in Windows

however，while the directory containes Chinese charactor，the slash will return the original path, which will not be converted according to the source code.

export default function slash(path) {
	const isExtendedLengthPath = /^\\\\\?\\/.test(path);
	const hasNonAscii = /[^\u0000-\u0080]+/.test(path); // eslint-disable-line no-control-regex

        // hit this statement and return the original path
	if (isExtendedLengthPath || hasNonAscii) {
		return path;
	}

	return path.replace(/\\/g, '/');
}

by the way, I found out that vite implements its own slash function in the utils file，but the test cases are still use the slash component，This is what caused the test cases run fail

···
export function slash(p: string): string {
return p.replace(/\/g, '/')
}
···

Close #3582

What is the purpose of this pull request?

• Bug fix