* Update authors to "jrnl contributors" to comply with GPL3
* Include jrnl email address with contributors
* Include GPL notice in jrnl --version
* Apply consistent copyright and license to all Python files
* Add copyright and license to documentation
* Add copyright and license to docs theme
* Wiping poetry cache to try to resolve a test issue
* Testing with Python 3.9.0 in attempt to bypass GitHub Actions failure in 3.9.1
* make format
* Exclude Windows Python 3.9 build which is failing due to a GitHub Actions problem
* Modify testing to get around this 3.9 issue...
* Fix exclude