Add Apache-2.0 license

[No767]

Summary

Finally open sourcing the project to use Apache-2.0.

Types of changes

What types of changes does your code introduce to Kanae?
Put an x in the boxes that apply

• Bugfix (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 not work as expected)
• Documentation Update (Updates to README.md, the documentation, etc)
• Other (if none of the other choices apply)

Checklist

Put an x in the boxes that apply

• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes. (if appropriate)
• All workflows (except pre-commit.ci) pass with my new changes
• This PR does not address a duplicate issue or PR

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