Merge pull request #971 from rackerlabs/renovate/python-swiftclient-4.x

chore(deps): update dependency python-swiftclient to v4.8.0

Author: cardoe

ironic-images/requirements.txt

@@ -1,4 +1,4 @@
 diskimage-builder==3.38.0
 ironic-python-agent-builder==6.0.0
 python-keystoneclient==5.6.0
-python-swiftclient==4.7.0
+python-swiftclient==4.8.0