Switch to Rocky 9 built external packages on Hercules

The workflow was updated to use modules built on Rocky 9, but the
external packages (like prepobs) were still pointing to the versions
built on CentOS (Orion). This transitions to packages built on Rocky
9.

workflow/hosts/hercules.yaml

@@ -1,4 +1,4 @@
-BASE_GIT: '/work/noaa/global/glopara/git'
+BASE_GIT: '/work/noaa/global/glopara/git_rocky9'
 DMPDIR: '/work/noaa/rstprod/dump'
 BASE_CPLIC: '/work/noaa/global/glopara/data/ICSDIR/prototype_ICs'
 PACKAGEROOT: '/work/noaa/global/glopara/nwpara'