chore: update license (#93)

added Copyright 2024 Defense Unicorns

## Description

...

## Related Issue

Fixes #64 
<!-- or -->
Relates to #

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [x] Other (security config, docs update, etc)

## Checklist before merging

- [ ] Test, docs, adr added or updated as needed
- [ ] [Contributor Guide
Steps](https://github.com/defenseunicorns/uds-package-mattermost/blob/main/CONTRIBUTING.md#developer-workflow)
followed

Co-authored-by: Wayne Starr <[email protected]>

LICENSE

@@ -186,7 +186,7 @@
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright [yyyy] [name of copyright owner]
+   Copyright 2024 Defense Unicorns
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.