fix line number for fastly

.gitlab/issue_templates/preflight_checks.md

@@ -34,7 +34,7 @@
         - Staging
             - GCP `gstg`: https://dev.gitlab.org/cookbooks/chef-repo/blob/master/roles/gstg-base-lb-fe.json#L48
         - Production
-            - GCP `gprd`: https://dev.gitlab.org/cookbooks/chef-repo/blob/master/roles/gprd-base-lb-fe.json#L48
+            - GCP `gprd`: https://dev.gitlab.org/cookbooks/chef-repo/blob/master/roles/gprd-base-lb-fe.json#L56
 
 
 ## Object storage