Update resolve-url-loader@^5.0.0 (with PostCSS v8) to avoid conflicts

[pushred]

This upgrades to the latest version of resolve-url-loader which itself upgrades to PostCSS@8. I have been encountering version conflicts related to this dependency and others that also depend on PostCSS that block CRA Webpack builds with this error:

> react-scripts build

Creating an optimized production build...
Failed to compile.

static/css/main.a6b5f62b.css from Css Minimizer plugin
Error: PostCSS plugin postcss-discard-comments requires PostCSS 8.
Migration guide for end-users:
https://github.com/postcss/postcss/wiki/PostCSS-8-for-end-users

The only usage of resolve-url-loader in react-scripts is requiring it in the Webpack config, so this upgrade is straightforward and in my testing causes no issue with the dev server or building for production.

I reported more details about the conflict here, including a reproduction:

storybookjs/storybook#19218

Currently I am working around this with npm v8's overrides feature.

[facebook-github-bot]

Hi @pushred!

Thank you for your pull request and welcome to our community.

Action Required

In order to merge any pull request (code, docs, etc.), we require contributors to sign our Contributor License Agreement, and we don't seem to have one on file for you.

Process

In order for us to review and merge your suggested changes, please sign at https://code.facebook.com/cla. If you are contributing on behalf of someone else (eg your employer), the individual CLA may not be sufficient and your employer may need to sign the corporate CLA.

Once the CLA is signed, our tooling will perform checks and validations. Afterwards, the pull request will be tagged with CLA signed. The tagging process may take up to 1 hour after signing. Please give it that time before contacting us about it.

If you have received this in error or have any questions, please contact us at cla@fb.com. Thanks!

[facebook-github-bot]

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Meta Open Source project. Thanks!

[facebook-github-bot]

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Meta Open Source project. Thanks!

[jpierson-at-riis]

The pipeline failures seem to be unavailable. What was breaking with this change. I'm running into the same problems and am looking for a solution for the override that @pushred mentioned. Is there a way to rerun these failing checks so that we can get more information?

[ansnoussi]

any updates on this ? 🤔
we have a security alert for "PostCSS line return parsing error" which was fixed in version 8.4.31 of postcss.
but resolve-url-loader only migrated to postcss 8 in version 5.0.0.