Update dependency hdkey to v2

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
hdkey	dependencies	major	^1.1.2 -> ^2.0.0

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Release Notes

cryptocoinjs/hdkey

### [`v2.0.1`](https://togithub.com/cryptocoinjs/hdkey/blob/master/CHANGELOG.md#​201--2020-05-30) [Compare Source](https://togithub.com/cryptocoinjs/hdkey/compare/2.0.0...2.0.1) - Bugfix: prevent mutating buffers passed in ([#​39](https://togithub.com/cryptocoinjs/hdkey/pull/39)) ### [`v2.0.0`](https://togithub.com/cryptocoinjs/hdkey/blob/master/CHANGELOG.md#​200--2020-05-29) [Compare Source](https://togithub.com/cryptocoinjs/hdkey/compare/1.1.2...2.0.0) - **BREAKING:** Require Node.js v10+ ([#​38](https://togithub.com/cryptocoinjs/hdkey/pull/38)) - Upgrade `secp256k1` dependency; to use N-API ([#​32](https://togithub.com/cryptocoinjs/hdkey/pull/32))

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