Add py-sniffio (#19170)

var/spack/repos/builtin/packages/py-sniffio/package.py

@@ -0,0 +1,20 @@
+# Copyright 2013-2020 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 import *
+
+
+class PySniffio(PythonPackage):
+    """This is a tiny package whose only purpose is to let you detect which
+    async library your code is running under."""
+
+    homepage = "https://github.com/python-trio/sniffio"
+    url      = "https://pypi.io/packages/source/s/sniffio/sniffio-1.1.0.tar.gz"
+
+    version('1.1.0', sha256='8e3810100f69fe0edd463d02ad407112542a11ffdc29f67db2bf3771afb87a21')
+
+    depends_on('py-setuptools', type='build')
+    depends_on('py-wheel', type='build')
+    depends_on('py-certifi')