sys.set_modtime: try no space time format

Author: scivision

+stdlib/+sys/set_modtime.m

@@ -5,7 +5,8 @@
 elseif ismac()
   cmd = sprintf("touch -mt %s %s", string(t, "yyyyMMddHHmm"), p);
 else
-  cmd = sprintf("touch -d '%s' %s", string(t, "yyyy-MM-dd HH:mm:ss"), p);
+  % https://man7.org/linux/man-pages/man1/touch.1.html
+  cmd = sprintf("touch -t %s %s", string(t, "yyyyMMddHHmm"), p);
 end
 
 [s, m] = system(cmd);