python-openpyxl: add missing checkdepends

python-py was brought in by older pytest [1][2]

[1] 6687aae
[2] pytest-dev/pytest#10396

git-svn-id: file:///srv/repos/svn-community/svn@1342284 9fca08f4-af9d-4005-b8df-a31f2cc04f65

trunk/PKGBUILD

@@ -12,7 +12,7 @@ url="https://openpyxl.readthedocs.org/"
 license=('MIT')
 depends=('python-et-xmlfile')
 makedepends=('python-setuptools')
-checkdepends=('python-pytest' 'python-lxml' 'python-pandas' 'python-pillow')
+checkdepends=('python-pytest' 'python-py' 'python-lxml' 'python-pandas' 'python-pillow')
 optdepends=('python-pillow: needed to include images'
             'python-lxml: alternative XML backend'
             'python-defusedxml: guard against various XML vulnerabilities'