build(deps-dev): bump webpack-merge from 4.2.2 to 5.1.4 in /frontend

[dependabot]

Bumps webpack-merge from 4.2.2 to 5.1.4.

Changelog

Sourced from webpack-merge's changelog.

5.1.4 / 2020-09-09

• Fix - Expose CustomizeRule for TypeScript users #147

5.1.3 / 2020-08-30

• Fix - Allow merging a RegExp to itself #145

5.1.2 / 2020-08-18

• Fix - Allow overriding an object field with null #144

5.1.1 / 2020-08-04

• Fix - Drop <reference types="webpack-dev-server" /> from index.d.ts #143

5.1.0 / 2020-08-03

• Feature - Expose merge as default for backwards-compatibility with TypeScript. Now import merge from "webpack-merge"; works there. In CommonJS, the default alias is exposed through default property due to technical constraints.

5.0.9 / 2020-07-09

• Fix - Don't crash on merge() and merge([]). Now {} is returned in these corner cases.

5.0.8 / 2020-07-07

• Fix - Support Node 10 #138

5.0.7 / 2020-07-06

• Fix - Drop tslib dependency by setting "importHelpers": false,

5.0.6 / 2020-07-06

• Fix - Add tslib to dependencies

5.0.5 / 2020-07-06

• Tech - Optimize build size (UMD isn't needed)

5.0.4 / 2020-07-06

• Documentation - Use CommonJS imports at the examples. #137

5.0.3 / 2020-07-06

• Feature - Support TypeScript out of the box. #84 #86 #95 #110 #112
• Deprecation - merge.smart has been dropped as it's tricky to support all the corner cases. Instead, it's better to use the provided utilities to put together a merge that fits your case.
• Deprecation - mergeStrategy has been dropped in favor of using mergeWithCustomize with customizeArray and customizeObject.
• Deprecation - merge.multiple has been dropped as the functionality was too specific and it's better to implement in the user space if needed.

Commits

• 4b917df 5.1.4
• c4e293b fix: Expose CustomizeRule for TypeScript users
• 10cf6ff chore: var -> let
• cf5b5fe chore: Resolve tests to ts during development
• fcd5167 5.1.3
• fd8449b fix: Allow merging a RegExp to itself
• 17fb00f fix: Drop .only from test
• f65cc3d 5.1.2
• 4eb811c fix: Allow overriding an object field with null
• 2e8780e 5.1.1
• Additional commits viewable in compare view

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[dependabot]

Superseded by #629.