try to fix lightning build on CI

Author: lopuhin

tox.ini

@@ -55,7 +55,7 @@ deps=
     Pillow
 commands=
     ; to install lightning numpy and Cython must be installed first
-    pip install Cython
+    pip install Cython 'setuptools < 60.0'
     pip install joblib "sklearn-contrib-lightning >= 0.4" --no-binary sklearn-contrib-lightning
     pip install -e .
     ; run tests for extra dependencies