Build: Move entry points and packages to pyproject

[glensc]

Looks like changes were incomplete from #2045

$ pipx install plextraktsync==0.31.11
Note: Dependent package 'python-dotenv' contains 1 apps
  - dotenv
Note: Dependent package 'charset-normalizer' contains 1 apps
  - normalizer
Note: Dependent package 'websocket-client' contains 1 apps
  - wsdump
Note: Dependent package 'markdown-it-py' contains 1 apps
  - markdown-it
Note: Dependent package 'pygments' contains 1 apps
  - pygmentize
Note: Dependent package 'tqdm' contains 1 apps
  - tqdm

No apps associated with package plextraktsync. Try again with '--include-deps' to include apps of dependent packages, which are listed above. If you are attempting to install a library, pipx should not be used. Consider using pip or a similar tool instead.