====== You are attempting to remove the meta-package 'proxmox-ve'! ======

When trying to upgrade grom ''8.4.19'' to ''9.2.1'':

<code bash>
W: (pve-apt-hook) !! WARNING !!
W: (pve-apt-hook) You are attempting to remove the meta-package 'proxmox-ve'!
W: (pve-apt-hook) 
W: (pve-apt-hook) If you really want to permanently remove 'proxmox-ve' from your system, run the following command
W: (pve-apt-hook) 	touch '/please-remove-proxmox-ve'
W: (pve-apt-hook) run apt purge proxmox-ve to remove the meta-package
W: (pve-apt-hook) and repeat your apt invocation.
W: (pve-apt-hook) 
W: (pve-apt-hook) If you are unsure why 'proxmox-ve' would be removed, please verify
W: (pve-apt-hook) 	- your APT repository settings
W: (pve-apt-hook) 	- that you are using 'apt full-upgrade' to upgrade your system
E: Sub-process /usr/share/proxmox-ve/pve-apt-hook returned an error code (1)
E: Failure running script /usr/share/proxmox-ve/pve-apt-hook
</code>

===== Solution =====

Add Proxmox's CEPH non-subscription repository.

===== Reason =====

Some default old Ceph packages were installed, like:
  * librbd1
  * libcephfs2
  * python3-ceph-argparse
  * python3-cephfs
  * python3-ceph-common
  * python3-rbd amd64  
  * librgw2 amd64
  * python3-rgw amd64
  * libradosstriper1
  * ceph-common
  * python3-rados
  * librados2
  * ceph-fuse