chore(main): release 8.4.0 (#268)
:robot: I have created a release *beep* *boop*
---
This release introduces a Hooks API. Hooks are collections of
user-defined callbacks that are executed by the SDK at various points of
interest. You can use them to augment the SDK with metrics or tracing.
##
[8.4.0](https://github.com/launchdarkly/ruby-server-sdk/compare/8.3.1...8.4.0)
(2024-04-05)
### Features
* Add initial support for hooks
([#256](https://github.com/launchdarkly/ruby-server-sdk/issues/256))
([3cf16eb](https://github.com/launchdarkly/ruby-server-sdk/commit/3cf16ebd559053cef601de288bddbc6430fe33ec))
### Bug Fixes
* Adjust migration variation and hook interaction
([#264](https://github.com/launchdarkly/ruby-server-sdk/issues/264))
([8067af6](https://github.com/launchdarkly/ruby-server-sdk/commit/8067af635e7adc726656ecf75d4395a30cb1e359))
---
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Co-authored-by: Matthew Keeler <mkeeler@launchdarkly.com>
