Aliases are not resolved for CSS URLs with fragments

[CyberAP]

Describe the bug

If you use URL fragments (url('foo#bar')) inside CSS they will not be resolved using aliases from Vite config.

Reproduction

https://stackblitz.com/edit/vitejs-vite-k7ay22?file=style.css

Steps to reproduce

1. Create an alias to an SVG sprite.
2. Reference one of the SVG sprites using that alias in CSS, example: background: url('my.svg#some-image')
3. Import should be resolved using the defined alias

When using reproduction link:

1. Inspect the first block (#fragment)
2. Remove the fragment from the source code (#test)
3. Notice how the background URL changes from url(fragment.svg#test) to url('/folder/fragment.svg')

System Info

System:
    OS: macOS 14.5
    CPU: (10) arm64 Apple M1 Pro
    Memory: 163.20 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.12.2 - ~/.asdf/installs/nodejs/20.12.2/bin/node
    Yarn: 1.22.19 - ~/.asdf/shims/yarn
    npm: 10.5.0 - ~/.asdf/plugins/nodejs/shims/npm
  Browsers:
    Chrome: 126.0.6478.127
    Chrome Canary: 128.0.6598.0
    Firefox: 127.0
    Safari: 17.5
    Safari Technology Preview: 18.0
  npmPackages:
    @vitejs/plugin-vue2: ^2.3.1 => 2.3.1 
    vite: ^5.3.3 => 5.3.3

Used Package Manager

yarn

Logs

No response

Validations

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• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
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• The provided reproduction is a minimal reproducible example of the bug.

[stackblitz]

Start a new pull request in StackBlitz Codeflow.

• vitejs-vite-k7ay22 (Open reproduction)