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

@@ -57,7 +57,7 @@ Unverified assumptions, to be checked against real hardware:
 
 ## Install
 
-Python 3.10 or later.
+Python 3.12 or later.
 
 ```bash
 pip install napalm-vmware