Don't match ARM64 when instance type starts with 'g'

Author: pmtk

scripts/aws/manage_aws_stack.sh

@@ -30,7 +30,7 @@ action_create() {
     local -r cf_tpl_file="${SCRIPTDIR}/cf-gen.yaml"
 
     local arch="x86_64"
-    if [[ "${inst_type%.*}" =~ .*"g".* ]]; then
+    if [[ "${inst_type%.*}" =~ .+"g".* ]]; then
         arch="arm64"
     fi