Update to latest version of libvirt-python inside tox.ini (aka
libvirt-python library which is used for the tests).
diff --git a/tox.ini b/tox.ini
index 83d786b..880185f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,7 +8,7 @@
     -r{toxinidir}/requirements-tests.txt
     pyopenssl
     lockfile
-    libvirt-python==4.0.0
+    libvirt-python==5.9.0
     py2.7: paramiko
     py3.7: setuptools==41.0.1
 commands = cp libcloud/test/secrets.py-dist libcloud/test/secrets.py
@@ -123,7 +123,7 @@
     paramiko
     pyopenssl
     python-dateutil
-    libvirt-python==4.0.0
+    libvirt-python==5.9.0
     lockfile
 set-env =
 commands = cp libcloud/test/secrets.py-dist libcloud/test/secrets.py
@@ -135,7 +135,7 @@
     -r{toxinidir}/requirements-tests.txt
     paramiko
     pyopenssl
-    libvirt-python==4.0.0
+    libvirt-python==5.9.0
     lockfile
 set-env =
 commands = cp libcloud/test/secrets.py-dist libcloud/test/secrets.py