Remove default argument in hookimpl overshadowing the runtime value,

see:  pytest-dev/pluggy#442 (comment)

Author: krassowski

Diff for: pylsp/plugins/references.py

@@ -8,7 +8,7 @@
 
 
 @hookimpl
-def pylsp_references(document, position, exclude_declaration=False):
+def pylsp_references(document, position, exclude_declaration):
     code_position = _utils.position_to_jedi_linecolumn(document, position)
     usages = document.jedi_script().get_references(**code_position)