Remove outdated sentence.

Co-authored-by: J0J0 Todos <2733783+JOJ0@users.noreply.github.com>

Author: Serene-Arc

CONTRIBUTING.rst

@@ -124,7 +124,7 @@ command. Instead, you can activate the virtual environment in your shell with:
 
     $ poetry env activate
 
-You should see ``(beets-py3.10)`` prefix in your shell prompt. Now you can run
+Now you can run
 commands directly, for example:
 
 ::