Modernize building process

[davelopez]

• Consider dropping Python 3.8 support Update server build tools + drop Python 3.8 #282
• Modernize the package building for the server https://packaging.python.org/en/latest/ Update server build tools + drop Python 3.8 #282
• Migrate to pygls v2 (Guide: https://pygls.readthedocs.io/en/latest/pygls/howto/migrate-to-v2.html)