Update gaeac6.intel.lua following maintenance (#1759)

# Description
Hat tip to @aerorahul for finding this is the needed solution to enable
building to resume on GaeaC6

Author: CoryMartin-NOAA

modulefiles/GDAS/gaeac6.intel.lua

@@ -76,6 +76,8 @@ load("py-xarray/2023.7.0")
 load("py-f90nml/1.4.3")
 load("py-pip/23.1.2")
 
+unload("cray-libsci")
+
 setenv("CC","cc")
 setenv("CXX","CC")
 setenv("FC","ftn")