chore: Python 3.12 is the floor, part A (#6)

The shared workflow tests on 3.12 and 3.13 by default and runs lowest on
3.12; the template declares requires-python >=3.12 with ruff and mypy on
3.12, and the tool itself needs 3.12. netOrk runs every driver on 3.12 in
its own containers.

check keeps accepting a 3.10 floor until every driver has moved; part B
raises it.

pyproject.toml

@@ -8,7 +8,7 @@ version = "0.1.0"
 description = "Rules, CI and release tooling shared by the drivers of the NAPALM org"
 readme = "README.md"
 license = "Apache-2.0"
-requires-python = ">=3.11"
+requires-python = ">=3.12"
 authors = [{ name = "Christian Manivong", email = "christian@manivong.de" }]
 dependencies = ["packaging>=23"]
 
@@ -30,13 +30,13 @@ napalm_standard = ["py.typed"]
 
 [tool.ruff]
 line-length = 100
-target-version = "py311"
+target-version = "py312"
 
 [tool.ruff.lint]
 select = ["E", "F", "I", "UP", "B"]
 
 [tool.mypy]
-python_version = "3.11"
+python_version = "3.12"
 strict = true
 
 [tool.pytest.ini_options]