fix: the floor on napalm is 5.1 (NAPALM/driver-standard#6)

napalm 5.0 and older import pkg_resources, which a Python 3.12 venv no
longer has, so the lowest job failed on them.

pyproject.toml

@@ -37,7 +37,7 @@ classifiers = [
     "Typing :: Typed",
 ]
 dependencies = [
-    "napalm>=4.0",
+    "napalm>=5.1",  # older releases import pkg_resources, which a 3.12 venv lacks
     "typing-extensions>=4.0",
 ]