Update dependency webpack-sources to v2.3.1

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
webpack-sources	2.3.0 -> 2.3.1

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Release Notes

webpack/webpack-sources

### [`v2.3.1`](https://togithub.com/webpack/webpack-sources/releases/v2.3.1) [Compare Source](https://togithub.com/webpack/webpack-sources/compare/v2.3.0...v2.3.1) ### Performance - fix type bug in CachedSource which lead to bad hashing performance

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Latest commit: 299db386efa65a85ed2f499e7fcc5f8dced89425

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