updated changelog for version 2.0.0a6 (Draegerwerk#258)

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## Types of changes
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- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)

## Checklist:
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- [x] I have updated the [changelog](../CHANGELOG.md) accordingly.
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CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [2.0.0a6] - 2023-09-11
+
 ### Added
 
 - `network` module to handle network adapter stuff of the host computer