chore: create license

[elijaholmos]

Development

• decide on a license that is appropriate for the scope of this OSS project
• create a LICENSE file in the root of the repository
• implement a Check License Header workflow modeled after https://github.com/elijaholmos/halo-discord-bot/blob/dev/.github/workflows/license-check.yml

Testing

• ensure LICENSE is accessible appropriate for the scope of the OSS project
• ensure Check License Header workflow model functions as expected