fix(config): compile type compatibility in css-loader v4

[EvanMaFYH]

set the css-loader's compileType option to icss

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

when nuxt upgrade the css-loader library to v4, it results in a break change
if you export your sass variables and import it in your vue file before, it works fine
however when the css-loader library is upgraded to v4, the css-loader's compileType option is module by default which causes the problem
for example:
in your variable.scss file

$primaryColor: blue;
:export{
  primaryColor: $primaryColor;
}

in your vue file

import variables from 'variable.scss'

before: we can get the expected value
now : the variables we get is '{}'

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly. (PR: #)
• I have added tests to cover my changes (if not applicable, please state why)
• All new and existing tests are passing.

[clarkdo]

Can you please update test snapshot ?

[EvanMaFYH]

Can you please update test snapshot ?

I have updated it