Update typescript-eslint monorepo to v3.9.0

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
@typescript-eslint/eslint-plugin	devDependencies	minor	3.8.0 -> 3.9.0
@typescript-eslint/parser	devDependencies	minor	3.8.0 -> 3.9.0

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Release Notes

typescript-eslint/typescript-eslint

### [`v3.9.0`](https://togithub.com/typescript-eslint/typescript-eslint/blob/master/CHANGELOG.md#​390-httpsgithubcomtypescript-eslinttypescript-eslintcomparev380v390-2020-08-10) [Compare Source](https://togithub.com/typescript-eslint/typescript-eslint/compare/v3.8.0...v3.9.0) ##### Bug Fixes - **eslint-plugin:** [no-throw-literal] support type assertions ([#​2354](https://togithub.com/typescript-eslint/typescript-eslint/issues/2354)) ([470174a](https://togithub.com/typescript-eslint/typescript-eslint/commit/470174ad51fdb12d82129a896559075513f6c912)) ##### Features - **eslint-plugin:** [no-unsafe-assignment/return] allow assigning any => unknown ([#​2371](https://togithub.com/typescript-eslint/typescript-eslint/issues/2371)) ([e7528e6](https://togithub.com/typescript-eslint/typescript-eslint/commit/e7528e686f5fe5cce8504fc15d3cd06b8733712e)) - **typescript-estree:** support TSv4 labelled tuple members ([#​2378](https://togithub.com/typescript-eslint/typescript-eslint/issues/2378)) ([00d84ff](https://togithub.com/typescript-eslint/typescript-eslint/commit/00d84ffbcbe9d0ec98bdb2f2ce59959a27ce4dbe))

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