Draft: Resolve "Ensure packer-plugin-proxmox is available in nexus"

General MR

Summary

Ensure packer-plugin-proxmox is available in nexus

The plugin in nexus is 1.2.1 at the moment, it may of been broken so previously we wanted to pin to 1.1.8 but will upgrade to 1.2.3 and see if it works

Relevant logs/screenshots

N/A

Linked Issue

issue also related to iso builder bigbang-edge-controller-iso-builder#480

Upgrade Notices

N/A

Closes #429 (moved)