fix(css): skip comma when matching css url

[ikeq]

Description

I think it would be better to fix the multiple css url issue by correcting the regex, original issue #3922.

Issue review:

The comma is removed when there are multiple url().

.test {
  background-image: url(foo.png),url(bar.png);
}

resulting in

.test {
  background-image: url(foo.png)url(bar.png);
}

Debugging

Issue fixed after correcting the regex:

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[antfu]

Duplicated with #3926?

[ikeq]

This pr revert #3926 by providing a better solution.