feat: declare that upgrading everything must be a full upgrade on Proxmox VE

A plain apt-get upgrade holds back what needs new or removed packages and
can leave a node half updated; Proxmox documents apt full-upgrade. netOrk
reads FULL_UPGRADE when it upgrades the host (MVP 5).

napalm_proxmox/driver.py

@@ -96,6 +96,10 @@ class ProxmoxDriver(
     USES_SSH = False
     # A PVE node reboots through a full init sequence plus storage checks.
     REBOOT_SETTLE_SECONDS = 90
+    #: "Upgrade everything" must be a full upgrade on Proxmox VE: a plain
+    #: ``apt-get upgrade`` holds back what needs new or removed packages and can
+    #: leave the node half updated. netOrk reads this when it upgrades the host.
+    FULL_UPGRADE = True
     PORT_SPECS = [
         PortSpec("https", 8006, weight=8.0),
     ]

tests/test_full_upgrade.py

@@ -0,0 +1,11 @@
+"""Proxmox VE says that "upgrade everything" must be a full upgrade on it.
+
+A plain ``apt-get upgrade`` can leave a node half updated; Proxmox documents
+``apt full-upgrade``. netOrk reads ``FULL_UPGRADE`` to choose.
+"""
+
+from napalm_proxmox.driver import ProxmoxDriver
+
+
+def test_a_full_upgrade_is_declared():
+    assert ProxmoxDriver.FULL_UPGRADE is True