feat: report the firmware Netgear offers, not a warning (0.4.0)

The Plus driver looked the newest firmware up in Netgear's download
catalogue and named firmware_update_available itself. It now reports
get_firmware_offer() (napalm-device-types 4.16 FirmwareOfferMixin): what
runs, the newest offered, whether that is newer by Netgear's versioning,
and the download link; netOrk names the warning (netOrk #1111). The Smart
driver's empty get_device_warnings goes too. Requires
napalm-device-types 4.16.0.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "napalm-netgear"
-version = "0.3.0"
+version = "0.4.0"
 description = "NAPALM driver for Netgear switches (Plus/Smart)"
 readme = "README.md"
 license = { text = "Apache-2.0" }
@@ -26,7 +26,7 @@ classifiers = [
 ]
 dependencies = [
     "napalm>=4.0.0",
-    "napalm-device-types>=4.13.0",
+    "napalm-device-types>=4.16.0",
     "netmiko>=4.0.0",
     "paramiko>=5.0.0",  # CVE-2026-44405
     "netaddr",