add py-etils from Spack upstream (dep of py-jax)

packages/py-etils/package.py

+# Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack.package import *
+
+
+class PyEtils(PythonPackage):
+    """etils (eclectic utils) is an open-source collection of utils
+    for python."""
+
+    homepage = "https://github.com/google/etils"
+    pypi = "etils/etils-0.9.0.tar.gz"
+
+    version("0.9.0", sha256="489103e9e499a566765c60458ee15d185cf0065f2060a4d16a68f8f46962ed0d")
+
+    variant("epath", default=False, description="with epath module")
+
+    depends_on("python@3.7:", type=("build", "run"))
+
+    depends_on("py-importlib-resources", type=("build", "run"), when="+epath")
+    depends_on("py-typing-extensions", type=("build", "run"), when="+epath")
+    depends_on("py-zipp", type=("build", "run"), when="+epath")
+
+    depends_on("py-flit-core@3.5:3", type="build")