Update License file to add copyright owner

[bradmccoydev]

Good first issue

In the license file on line 189 the authors haven't been stated, this is a common thing that people miss when adding apache2 licenses.

replace the text with:

Copyright 2023 The cdevents Authors

[rjalander]

Thanks @adamkenihan, fixed with this PR https://github.com/cdevents/sdk-java/pull/57,