fix(build): don't rewrite CSS urls starting with $

[prymitive]

Description

URL might be a variable rather than a string.
When vite attempts to rewrite a variable it might produce bogus output as it doesn't know what value given variable holds.

Currently this can cause a build error like the one below:

Error: expected ")".
  ╷
9 │   @import url(../../node_modules/bootswatch/dist/darkly/$web-font-path);
  │               ^
  ╵
  node_modules/bootswatch/dist/darkly/_bootswatch.scss 9:15  @import
  src/Styles/DarkTheme.scss 75:9                             @import
  src/Styles/DarkThemeLoader.scss 2:11                       root stylesheet
error during build:
Error: expected ")".

See https://github.com/thomaspark/bootswatch/blob/52649a617b7f66f0e8bc8128926a5c195ea7a5b4/dist/darkly/_bootswatch.scss#L7-L10

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• 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.

[prymitive]

Error: getaddrinfo ENOTFOUND playwright.azureedge.net

test failure seems unrelated