Update USER_SUBMITTED_GUIDES.md

How-to: Proxmox VE 7.4 to 8.0 Upgrade

USER_SUBMITTED_GUIDES.md

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 [Frigate VM on Proxmox with PCIe Coral TPU](https://www.derekseaman.com/2023/06/home-assistant-frigate-vm-on-proxmox-with-pcie-coral-tpu.html)
 
 [Moving Home Assistant’s Database To MariaDB On Proxmox](https://smarthomescene.com/guides/moving-home-assistants-database-to-mariadb-on-proxmox/)
+
+[How-to: Proxmox VE 7.4 to 8.0 Upgrade](https://www.derekseaman.com/2023/06/how-to-proxmox-7-4-to-8-0-upgrade.html)