`python-language-server` deprecated, switch to `python-lsp-server`.

[codeSamuraii]

Summary

python-language-server on which this Atom package depends is deprecated in favor of python-lsp-server, as confirmed by this issue and the long list of projects mentioning it underneath.

• The installation instructions for ide-python still mention installing the deprecated repo.
• The plugin defaults to the old version if the newer one is not found, as https://github.com/atom-community/ide-python/pull/389 shows.

Motivation

• Allow future PLSP features to improve this package while keeping an up-to-date Langage Server backend.

Describe alternatives you've considered

I just installed the correct version, and everything worked as expected.