Update module github.com/peterbourgon/diskv to v3 (master) - autoclosed

[mend-for-github-com[bot]]

This PR contains the following updates:

Package	Type	Update	Change
github.com/peterbourgon/diskv	require	major	v0.0.0-20171120014656-2973218375c3 -> v3.0.1

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Release Notes

peterbourgon/diskv

### [`v3.0.1`](https://togithub.com/peterbourgon/diskv/compare/v3.0.0...v3.0.1) [Compare Source](https://togithub.com/peterbourgon/diskv/compare/v3.0.0...v3.0.1) ### [`v3.0.0`](https://togithub.com/peterbourgon/diskv/releases/v3.0.0) [Compare Source](https://togithub.com/peterbourgon/diskv/compare/v2.0.1...v3.0.0) Major version bump due to addition of go.mod. ### [`v2.0.1`](https://togithub.com/peterbourgon/diskv/releases/v2.0.1) [Compare Source](https://togithub.com/peterbourgon/diskv/compare/v2.0.0...v2.0.1) Adds support for atomic filesystem ops via a new TempDir option. ### [`v2.0.0`](https://togithub.com/peterbourgon/diskv/releases/v2.0.0) [Compare Source](https://togithub.com/peterbourgon/diskv/compare/v1.0.0...v2.0.0) Breaking changes made to the Index option. We replace the implementation based on [petar/GoLLRB](https://togithub.com/petar/GoLLRB) with one based on [google/btree](https://togithub.com/google/btree). See issue [#​28](https://togithub.com/peterbourgon/diskv/issues/28).

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