fix: Rspack cssParser will parse failed when url(' ')

[cbbfcd]

Summary

fix 8788

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

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[codspeed-hq]

CodSpeed Performance Report

Merging #8822 will not alter performance

_{Comparing cbbfcd:fix/empty-url (190e399) with main (a4aa3a9)}

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Curious about what's new? Visit our releases page to delve into all the awesome details about this new version.

Summary

✅ 3 untouched benchmarks

[cbbfcd]

CLA problem, i will re-pr.