requirements: Pin xgboost only on macos

Author: ales-erjavec

requirements-core.txt

@@ -19,7 +19,8 @@ requests
 scikit-learn>=1.5.1
 scipy>=1.9
 serverfiles		# for Data Sets synchronization
-xgboost>=1.7.4,<2.1
+xgboost>=1.7.4,<2.1; sys_platform=="darwin"
+xgboost>=1.7.4; sys_platform!="darwin"
 # Reading Excel files
 xlrd>=1.2.0
 # Writing Excel Files

tox.ini

@@ -61,7 +61,7 @@ deps =
     oldest: scikit-learn==1.5.1
     oldest: scipy==1.10
     # oldest: serverfiles
-    oldest: xgboost==1.7.4
+    oldest: xgboost==2.1.0
     oldest: xlrd==1.2.0
     # oldest: xlsxwriter