Update dependency socket.io to v4

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
socket.io	^3.0.0 -> ^4.0.0

---

Release Notes

socketio/socket.io

### [`v4.0.0`](https://togithub.com/socketio/socket.io/blob/master/CHANGELOG.md#​400-httpsgithubcomsocketiosocketiocompare312400-2021-03-10) [Compare Source](https://togithub.com/socketio/socket.io/compare/3.1.2...4.0.0) ##### Bug Fixes - make io.to(...) immutable ([ac9e8ca](https://togithub.com/socketio/socket.io/commit/ac9e8ca6c71e00d4af45ee03f590fe56f3951186)) ##### Features - add some utility methods ([b25495c](https://togithub.com/socketio/socket.io/commit/b25495c069031674da08e19aed68922c7c7a0e28)) - add support for typed events ([#​3822](https://togithub.com/socketio/socket.io/issues/3822)) ([0107510](https://togithub.com/socketio/socket.io/commit/0107510ba8a0f148c78029d8be8919b350feb633)) - allow to exclude specific rooms when broadcasting ([#​3789](https://togithub.com/socketio/socket.io/issues/3789)) ([7de2e87](https://togithub.com/socketio/socket.io/commit/7de2e87e888d849eb2dfc5e362af4c9e86044701)) - allow to pass an array to io.to(...) ([085d1de](https://togithub.com/socketio/socket.io/commit/085d1de9df909651de8b313cc6f9f253374b702e)) #### [3.1.2](https://togithub.com/socketio/socket.io/compare/3.1.1...3.1.2) (2021-02-26) ##### Bug Fixes - ignore packets received after disconnection ([494c64e](https://togithub.com/socketio/socket.io/commit/494c64e44f645cbd24c645f1186d203789e84af0)) #### [3.1.1](https://togithub.com/socketio/socket.io/compare/3.1.0...3.1.1) (2021-02-03) ##### Bug Fixes - properly parse the CONNECT packet in v2 compatibility mode ([6f4bd7f](https://togithub.com/socketio/socket.io/commit/6f4bd7f8e7c41a075a8014565330a77c38b03a8d)) - **typings:** add return types and general-case overload signatures ([#​3776](https://togithub.com/socketio/socket.io/issues/3776)) ([9e8f288](https://togithub.com/socketio/socket.io/commit/9e8f288ca9f14f91064b8d3cce5946f7d23d407c)) - **typings:** update the types of "query", "auth" and "headers" ([4f2e9a7](https://togithub.com/socketio/socket.io/commit/4f2e9a716d9835b550c8fd9a9b429ebf069c2895))

---

Renovate configuration

:date: Schedule: "before 2am" (UTC).

:vertical_traffic_light: Automerge: Disabled by config. Please merge this manually once you are satisfied.

:recycle: Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

:no_bell: Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by WhiteSource Renovate. View repository job log here.