Move to nanobind 3.1 and release 8.0.1.3

The handle caster follows nanobind 3's renamed detail API (keep_alive_cb,
NB_CALL(nb_type_put), uint32_t caster flags). Bound surface unchanged per
sigdiff; list iteration ~4x faster.

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ["scikit-build-core>=0.11", "nanobind>=2.7,<3"]
+requires = ["scikit-build-core>=0.11", "nanobind>=3.1,<4"]
 build-backend = "scikit_build_core.build"
 
 [project]
@@ -9,7 +9,7 @@ name = "n3xd-ocp"
 # .devN suffix: the registry never allows republishing a version, and its
 # cleanup rule collects only the dev ones.  CMake asserts the prefix matches
 # the OCCT it found.
-version = "8.0.1.2"
+version = "8.0.1.3"
 description = "nanobind bindings for the OpenCASCADE geometry kernel (drop-in OCP)"
 readme = "README.md"
 requires-python = ">=3.12"