Add new package:py-pytest-check-links (#16503)

var/spack/repos/builtin/packages/py-pytest-check-links/package.py

+# 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 PyPytestCheckLinks(PythonPackage):
+    """pytest plugin that checks URLs for HTML-containing files."""
+
+    homepage = "https://github.com/jupyterlab/pytest-check-links"
+    url      = "https://pypi.io/packages/source/p/pytest-check-links/pytest_check_links-0.3.4.tar.gz"
+
+    version('0.3.4', sha256='4b3216548431bf9796557e8ee8fd8e5e77a69a4690b3b2f9bcf6fb5af16a502b')
+
+    depends_on('py-setuptools@17.1:', type='build')
+    depends_on('py-pbr@1.9:', type='build')