feat(py-traittypes): copy package from upstream

from https://github.com/spack/spack/commit/b0afb619dea4d593335d0b6db3facbf789b80bba

packages/py-traittypes/package.py

+# Copyright Spack Project Developers. See COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack.package import *
+
+
+class PyTraittypes(PythonPackage):
+    """Custom trait types for scientific computing."""
+
+    homepage = "http://ipython.org/"
+    pypi = "traittypes/traittypes-0.2.1.tar.gz"
+
+    license("BSD")
+
+    version("0.2.1", sha256="be6fa26294733e7489822ded4ae25da5b4824a8a7a0e0c2dccfde596e3489bd6")
+
+    depends_on("py-setuptools", type="build")
+    depends_on("py-traitlets@4.2.2:", type=("build", "run"))