aws-c-event-stream 0.5.9

[BrewTestBot]

Created by brew bump

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Created with brew bump-formula-pr.

release notes

## What's Changed
* Fix bind failure by @sfod in https://github.com/awslabs/aws-c-event-stream/pull/138
Full Changelog: https://github.com/awslabs/aws-c-event-stream/compare/v0.5.8...v0.5.9

View the full release notes at https://github.com/awslabs/aws-c-event-stream/releases/tag/v0.5.9.

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