Change some parm files to use bash

 On branch feature/gefs_v13_atmos_prep
	modified:   parm/gefs_atmos_ensavg_netcdf.parm
	modified:   parm/gefs_atmos_prep.parm
	modified:   parm/gefs_gempak.parm
	modified:   parm/gefs_init.parm

Refs: NOAA-EMC#96, NOAA-EMC#87 & NOAA-EMC#98

parm/gefs_atmos_ensavg_netcdf.parm

@@ -1,4 +1,4 @@
-#!/bin/ksh
+#! /usr/bin/env bash
 
 export HOMEgfs=${HOMEgfs:-$HOMEgefs}
 export EXECgfs=$HOMEgfs/exec

parm/gefs_atmos_prep.parm

@@ -1,4 +1,4 @@
-#!/bin/ksh
+#! /usr/bin/env bash
 
 case $cyc in
   00) memshift=0;;

parm/gefs_gempak.parm

@@ -1,4 +1,4 @@
-#!/bin/ksh
+#! /usr/bin/env bash
 
 export fstart=${fstart:-0}
 export fend=${fhmaxh:-384}

parm/gefs_init.parm

@@ -1,4 +1,4 @@
-#!/bin/ksh
+#! /usr/bin/env bash
 
 export warm_start=".false."