Update dependency ts-loader to v7

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
ts-loader	devDependencies	major	^6.2.1 -> ^7.0.0

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Release Notes

TypeStrong/ts-loader

### [`v7.0.0`](https://togithub.com/TypeStrong/ts-loader/blob/master/CHANGELOG.md#v700) [Compare Source](https://togithub.com/TypeStrong/ts-loader/compare/v6.2.2...v7.0.0) - [Project reference support enhancements](https://togithub.com/TypeStrong/ts-loader/pull/1076) - thanks [@​sheetalkamat](https://togithub.com/sheetalkamat)! - Following the end of life of Node 8, `ts-loader` no longer supports Node 8 **BREAKING CHANGE**

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