[ci] gzip:2 instead of gzip:6 for artifacts

on Linux and Mac.

Author: dpiparo

.github/workflows/root-ci-config/build_root.py

@@ -46,8 +46,7 @@
 
 WINDOWS = (os.name == 'nt')
 WORKDIR = (os.environ['HOME'] + '/ROOT-CI') if not WINDOWS else 'C:/ROOT-CI'
-COMPRESSIONLEVEL = 6 if not WINDOWS else 1
-
+COMPRESSIONLEVEL = 1 if WINDOWS else 2
 
 def main():
     # openstack.enable_logging(debug=True)