Octokit recommends dependencies be specified at 2 digits of precision:

> This library aims to adhere to Semantic Versioning 2.0.0. Violations of this scheme should be reported as bugs. Specifically, if a minor or patch version is released that breaks backward compatibility, that version should be immediately yanked and/or a new version should be immediately released that restores compatibility. Breaking changes to the public API will only be introduced with new major versions. As a result of this policy, you can (and should) specify a dependency on this gem using the Pessimistic Version Constraint with two digits of precision. For example:

```
spec.add_dependency 'octokit', '~> 2.0'
```

(See the bottom of https://github.com/octokit/octokit.rb)

Since 2.1.x is out, we can specify ~> 2.1. They should only introduce non-breaking changes up to 3.0, so this dependency will allow party_foul to work with 2.1.x-2.9.x.