Log Message:
yarn: Update to 1.13.0.

## 1.13.0

- Implements a new `package.json` field: `peerDependenciesMeta`

  [6671](https://github.com/yarnpkg/yarn/pull/6671) - [**Maël \ 
Nison**](https://twitter.com/arcanis)

- Adds an `optional` settings to `peerDependenciesMeta` to silence missing peer \ 
dependency warnings

  [6671](https://github.com/yarnpkg/yarn/pull/6671) - [**Maël \ 
Nison**](https://twitter.com/arcanis)

- Implements `yarn policies set-version [range]`. Check [the documentation]() \ 
for usage & tips.

  [6673](https://github.com/yarnpkg/yarn/pull/6673) - [**Maël \ 
Nison**](https://twitter.com/arcanis)

- Fixes a resolution issue when a package had an invalid `main` entry

  [6682](https://github.com/yarnpkg/yarn/pull/6682) - [**Maël \ 
Nison**](https://twitter.com/arcanis)

- Decreases the size of the generated `$PATH` environment variable for a better \ 
Windows support

  [6683](https://github.com/yarnpkg/yarn/issues/6683) - [**Rowan \ 
Lonsdale**](https://github.com/hWorblehat)

- Fixes postinstall scripts for third-party packages when they were referencing \ 
a binary from their own dependencies

  [6712](https://github.com/yarnpkg/yarn/pull/6712) - [**Maël \ 
Nison**](https://twitter.com/arcanis)

- Fixes yarn audit exit code overflow

  [6748](https://github.com/yarnpkg/yarn/issues/6748) - [**Andrey \ 
Vetlugin**](https://github.com/antrew)

- Stops automatically unplugging packages with postinstall script when running \ 
under `--ignore-scripts`

  [6820](https://github.com/yarnpkg/yarn/pull/6820) - [**Maël \ 
Nison**](https://twitter.com/arcanis)

- Adds transparent support for the \ 
[`resolve`](https://github.com/browserify/resolve) package when using \ 
Plug'n'Play

  [6816](https://github.com/yarnpkg/yarn/pull/6816) - [**Maël \ 
Nison**](https://twitter.com/arcanis)

- Properly reports the error codes when the npm registry throws 500's

  [6817](https://github.com/yarnpkg/yarn/pull/6817) - [**Maël \ 
Nison**](https://twitter.com/arcanis)