chore(deps): update dependency lint-staged to v8 (#1986)

This PR contains the following updates:

| Package | Type | Update | Change | References |
|---|---|---|---|---|
| lint-staged | devDependencies | major | `7.3.0` -> `8.1.0` | [source](https://renovatebot.com/gh/okonet/lint-staged) |

---

### Release Notes

<details>
<summary>okonet/lint-staged</summary>

### [`v8.1.0`](https://renovatebot.com/gh/okonet/lint-staged/releases/v8.1.0)

[Compare Source](https://renovatebot.com/gh/okonet/lint-staged/compare/v8.0.5...v8.1.0)

### [8.1.0](http://git+https/github.com/okonet/lint-staged/compare/v8.0.5...v8.1.0) (2018-11-21)

##### Features

-   Add `relative` option to allow passing relative paths to linters ([#&#8203;534](http://git+https/github.com/lint-staged/lint-staged/issues/534)) ([fcb774b](http://git+https/github.com/okonet/lint-staged/commit/fcb774b))

### [`v8.0.5`](https://renovatebot.com/gh/okonet/lint-staged/releases/v8.0.5)

[Compare Source](https://renovatebot.com/gh/okonet/lint-staged/compare/v8.0.4...v8.0.5)

#### [8.0.5](http://git+https/github.com/okonet/lint-staged/compare/v8.0.4...v8.0.5) (2018-11-17)

##### Bug Fixes

-   Use listr-update-renderer from npm ([#&#8203;542](http://git+https/github.com/lint-staged/lint-staged/issues/542)) ([503110d](http://git+https/github.com/okonet/lint-staged/commit/503110d)), closes [#&#8203;533](http://git+https/github.com/lint-staged/lint-staged/issues/533)

### [`v8.0.4`](https://renovatebot.com/gh/okonet/lint-staged/releases/v8.0.4)

[Compare Source](https://renovatebot.com/gh/okonet/lint-staged/compare/v8.0.3...v8.0.4)

#### [8.0.4](http://git+https/github.com/okonet/lint-staged/compare/v8.0.3...v8.0.4) (2018-10-31)

##### Bug Fixes

-   **package:** update staged-git-files to version 1.1.2 ([ce434d3](http://git+https/github.com/okonet/lint-staged/commit/ce434d3))

### [`v8.0.3`](https://renovatebot.com/gh/okonet/lint-staged/releases/v8.0.3)

[Compare Source](https://renovatebot.com/gh/okonet/lint-staged/compare/v8.0.2...v8.0.3)

#### [8.0.3](http://git+https/github.com/okonet/lint-staged/compare/v8.0.2...v8.0.3) (2018-10-30)

##### Bug Fixes

-   Allow to use lint-staged on CI ([#&#8203;523](http://git+https/github.com/lint-staged/lint-staged/issues/523)) ([225a904](http://git+https/github.com/okonet/lint-staged/commit/225a904))

### [`v8.0.2`](https://renovatebot.com/gh/okonet/lint-staged/releases/v8.0.2)

[Compare Source](https://renovatebot.com/gh/okonet/lint-staged/compare/v8.0.1...v8.0.2)

#### [8.0.2](http://git+https/github.com/okonet/lint-staged/compare/v8.0.1...v8.0.2) (2018-10-29)

##### Bug Fixes

-   **git:** Use resolveGitDir in hasPartiallyStagedFiles ([#&#8203;520](http://git+https/github.com/lint-staged/lint-staged/issues/520)) ([af99172](http://git+https/github.com/okonet/lint-staged/commit/af99172)), closes [#&#8203;514](http://git+https/github.com/lint-staged/lint-staged/issues/514)

### [`v8.0.1`](https://renovatebot.com/gh/okonet/lint-staged/releases/v8.0.1)

[Compare Source](https://renovatebot.com/gh/okonet/lint-staged/compare/v8.0.0...v8.0.1)

#### [8.0.1](http://git+https/github.com/okonet/lint-staged/compare/v8.0.0...v8.0.1) (2018-10-29)

##### Bug Fixes

-   **git:** Use resolveGitDir to resolve to .git for git commands ([#&#8203;518](http://git+https/github.com/lint-staged/lint-staged/issues/518)) ([da42f8a](http://git+https/github.com/okonet/lint-staged/commit/da42f8a)), closes [#&#8203;514](http://git+https/github.com/lint-staged/lint-staged/issues/514)

### [`v8.0.0`](https://renovatebot.com/gh/okonet/lint-staged/releases/v8.0.0)

[Compare Source](https://renovatebot.com/gh/okonet/lint-staged/compare/v7.3.0...v8.0.0)

### [8.0.0](http://git+https/github.com/okonet/lint-staged/compare/v7.3.0...v8.0.0) (2018-10-29)

##### Features

-   Add support for partially staged files ([#&#8203;75](http://git+https/github.com/lint-staged/lint-staged/issues/75)) ([f82443c](http://git+https/github.com/okonet/lint-staged/commit/f82443c)), closes [#&#8203;62](http://git+https/github.com/lint-staged/lint-staged/issues/62)

##### BREAKING CHANGES

-   Node >= 8.6 is required

</details>

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