Fix data-files spec in setup.cfg

Author: krassowski

python_packages/jupyter_lsp/setup.cfg

@@ -31,9 +31,9 @@ python_requires = >=3.8
 install_requires =
     jupyter_server >=1.1.2
     importlib_metadata >=4.8.3 ; python_version<"3.10"
-data_files =
-    etc/jupyter/jupyter_server_config.d = jupyter_lsp/etc/jupyter-lsp-jupyter-server.json
 
+[options.data_files]
+etc/jupyter/jupyter_server_config.d = jupyter_lsp/etc/jupyter-lsp-jupyter-server.json
 
 [options.entry_points]
 jupyter_lsp_spec_v1 =