Update Packer.gitlab-ci.yml to use latest image

changelogs/unreleased/khair1-master-patch-79459.yml

+---
+title: Update Packer.gitlab-ci.yml to use latest image
+merge_request:
+author: Kelly Hair
+type: other

lib/gitlab/ci/templates/Packer.gitlab-ci.yml

 image:
-  name: hashicorp/packer:1.0.4
+  name: hashicorp/packer:latest
   entrypoint:
     - '/usr/bin/env'
     - 'PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'