dev-python/pygal: fix build when pytest-runner isn't installed

Closes: https://bugs.gentoo.org/658420
Package-Manager: Portage-2.3.40, Repoman-2.3.9

dev-python/pygal/pygal-2.4.0.ebuild

@@ -38,6 +38,8 @@ DOCS=( docs/changelog.rst README.md )
 
 python_prepare_all() {
 	sed -i "/sphinx.ext.intersphinx/d" docs/conf.py || die
+	# Not actually required unless we want to do setup.py test
+	sed -i "s/'pytest-runner'\(,\)\?//" setup.py || die
 	distutils-r1_python_prepare_all
 }