Update rand_core requirement from 0.5.1 to 0.6.3

[dependabot-preview[bot]]

Updates the requirements on rand_core to permit the latest version.

Changelog

Sourced from rand_core's changelog.

[0.6.3] - 2019-01-04

Fixes

• Make the std feature require the optional rand_os dependency (#675)
• Re-export the optional WASM dependencies of rand_os from rand to avoid breakage (#674)

[0.6.2] - 2019-01-04

Additions

• Add Default for ThreadRng (#657)
• Move rngs::OsRng to rand_os sub-crate; clean up code; use as dependency (#643) ##BLOCKER##
• Add rand_xoshiro sub-crate, plus benchmarks (#642, #668)

Fixes

• Fix bias in UniformInt::sample_single (#662)
• Use autocfg instead of rustc_version for rustc version detection (#664)
• Disable i128 and u128 if the target_os is emscripten (#671: work-around Emscripten limitation)
• CI fixes (#660, #671)

Optimisations

• Optimise memory usage of UnitCircle and UnitSphereSurface distributions (no PR)

[0.6.1] - 2018-11-22

• Support sampling Duration also for no_std (only since Rust 1.25) (#649)
• Disable default features of libc (#647)

[0.6.0] - 2018-11-14

Project organisation

• Rand has moved from rust-lang-nursery to rust-random! (#578)
• Created The Rust Random Book (source)
• Update copyright and licence notices (#591, #611)
• Migrate policy documentation from the wiki (#544)

Platforms

• Add fork protection on Unix (#466)
• Added support for wasm-bindgen. (#541, #559, #562, #600)
• Enable OsRng for powerpc64, sparc and sparc64 (#609)
• Use syscall from libc on Linux instead of redefining it (#629)

RNGs

• Switch SmallRng to use PCG (#623)
• Implement Pcg32 and Pcg64Mcg generators (#632)
• Move ISAAC RNGs to a dedicated crate (#551)
• Move Xorshift RNG to its own crate (#557)
• Move ChaCha and HC128 RNGs to dedicated crates (#607, #636)
• Remove usage of Rc from ThreadRng (#615)

Sampling and distributions

• Implement Rng.gen_ratio() and Bernoulli::new_ratio() (#491)

... (truncated)

Commits

• 8792268 Merge pull request #1137 from rust-random/work2
• 1bfc53d Update changelogs and bump version numbers
• 4534311 Merge pull request #1133 from rust-random/work2
• 81f1af8 Correct usage of reserve
• fa17d1c Add comment to append_string for Standard
• b4c1d66 Add DistString
• 1947c89 Move Distribution trait and associates to sub-module
• 98a0339 Merge pull request #1135 from dhardy/work
• a7f8fb7 Prepare rand_chacha v0.3.1 release
• 09d3df3 Merge pull request #1130 from dhardy/work
• Additional commits viewable in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

Dependabot will not automatically merge this PR because this dependency is pre-1.0.0.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot merge` will merge this PR after your CI passes on it - `@dependabot squash and merge` will squash and merge this PR after your CI passes on it - `@dependabot cancel merge` will cancel a previously requested merge and block automerging - `@dependabot reopen` will reopen this PR if it is closed - `@dependabot close` will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually - `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself) - `@dependabot use these labels` will set the current labels as the default for future PRs for this repo and language - `@dependabot use these reviewers` will set the current reviewers as the default for future PRs for this repo and language - `@dependabot use these assignees` will set the current assignees as the default for future PRs for this repo and language - `@dependabot use this milestone` will set the current milestone as the default for future PRs for this repo and language - `@dependabot badge me` will comment on this PR with code to add a "Dependabot enabled" badge to your readme Additionally, you can set the following in your Dependabot [dashboard](https://app.dependabot.com): - Update frequency (including time of day and day of week) - Pull request limits (per update run and/or open at any time) - Automerge options (never/patch/minor, and dev/runtime dependencies) - Out-of-range updates (receive only lockfile updates, if desired) - Security updates (receive only security updates, if desired)