chore: Python 3.12 is the floor (NAPALM/driver-standard#6)

netOrk runs every driver in its own containers on Python 3.12, so 3.10
and 3.11 are no longer supported or tested. requires-python, mypy and
ruff move to 3.12, along with what ruff's pyupgrade rules then rewrite.

README.md

@@ -12,7 +12,7 @@ It supports all three networking domains of Proxmox VE:
 
 ## Requirements
 
-- Python ≥ 3.10
+- Python ≥ 3.12
 - NAPALM ≥ 5.0.0
 - napalm-device-types ≥ 4.22.0
 - proxmoxer ≥ 2.0.0