Update dependency helmet to v3.21.2 - autoclosed

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
helmet (source)	dependencies	minor	3.19.0 -> 3.21.2

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Release Notes

helmetjs/helmet

### [`v3.21.2`](https://togithub.com/helmetjs/helmet/blob/master/CHANGELOG.md#​3212---2019-10-21) [Compare Source](https://togithub.com/helmetjs/helmet/compare/v3.21.1...v3.21.2) ##### Changed - Updated `helmet-csp` to v2.9.4 - Updated `bowser` subdependency from 2.6.1 to 2.7.0. See [helmet-csp#​94](https://togithub.com/helmetjs/csp/pull/94) ### [`v3.21.1`](https://togithub.com/helmetjs/helmet/blob/master/CHANGELOG.md#​3211---2019-09-20) [Compare Source](https://togithub.com/helmetjs/helmet/compare/v3.21.0...v3.21.1) ##### Fixed - Updated `helmet-csp` to v2.9.2 - Fixed a bug where a request from Firefox 4 could delete `default-src` from future responses - Fixed tablet PC detection by updating `bowser` subdependency to latest version ### [`v3.21.0`](https://togithub.com/helmetjs/helmet/blob/master/CHANGELOG.md#​3210---2019-09-04) [Compare Source](https://togithub.com/helmetjs/helmet/compare/v3.20.1...v3.21.0) ##### Added - Updated `x-xss-protection` to v1.3.0 - Added `mode: null` to disable `mode=block` ##### Changed - Updated `helmet-csp` to v2.9.1 - Updated `bowser` subdependency from 2.5.3 to 2.5.4. See [helmet-csp#​88](https://togithub.com/helmetjs/csp/pull/88) ### [`v3.20.1`](https://togithub.com/helmetjs/helmet/blob/master/CHANGELOG.md#​3201---2019-08-28) [Compare Source](https://togithub.com/helmetjs/helmet/compare/v3.20.0...v3.20.1) ##### Changed - Updated `helmet-csp` to v2.9.0 ### [`v3.20.0`](https://togithub.com/helmetjs/helmet/blob/master/CHANGELOG.md#​3200---2019-07-24) [Compare Source](https://togithub.com/helmetjs/helmet/compare/v3.19.0...v3.20.0) ##### Changed - Updated `helmet-csp` to v2.8.0

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