[Doppins] Upgrade dependency file-loader to ^4.0.0

[doppins-bot]

Hi!

A new version was just released of file-loader, so Doppins
has upgraded your project's dependency ranges.

Make sure that it doesn't break anything, and happy merging!

---

Upgraded file-loader from ^2.0.0 to ^3.0.0

Changelog:

Version 3.0.0

3.0.0 (https://github.com/webpack-contrib/file-loader/compare/v2.0.0...v3.0.0) (2018-12-20)

Code Refactoring

• drop support for webpack < 4 (#303](https://github.com/webpack-contrib/file-loader/issues/303)) ([203a4ee (https://github.com/webpack-contrib/file-loader/commit/203a4ee))
• more validations in options schema

Features

• resourcePath is now available in outputPath and publicPath (#304](https://github.com/webpack-contrib/file-loader/issues/304)) ([0d66e64 (https://github.com/webpack-contrib/file-loader/commit/0d66e64))
• context is now available in outputPath and publicPath (#305](https://github.com/webpack-contrib/file-loader/issues/305)) ([d5eb823 (https://github.com/webpack-contrib/file-loader/commit/d5eb823))

BREAKING CHANGES

• removed the useRelativePath option. It is dangerously and break url when you use multiple entry points.
• drop support for webpack < 4

[doppins-bot]

An additional new version was just released of file-loader, so we've added an
extra commit upgrading your range to ^3.0.1.

Hope that's alright!
— Doppins

[doppins-bot]

An additional new version was just released of file-loader, so we've added an
extra commit upgrading your range to ^4.0.0.

Hope that's alright!
— Doppins