fix(import): remove non-existent server module

[frascuchon]

Description

This PR remove the non-existent "server" module from __init__ definitions so users can import everything without errors:

from argilla import *

Type of change

(Please delete options that are not relevant. Remember to title the PR according to the type of change)

• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested

(Please describe the tests that you ran to verify your changes. And ideally, reference tests)

• Test A
• Test B

Checklist

• I followed the style guidelines of this project
• I did a self-review of my code
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I filled out the contributor form (see text above)
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)