Bump python-openstackclient from 6.6.1 to 7.0.0

Bumps [python-openstackclient](https://docs.openstack.org/python-openstackclient/latest/) from 6.6.1 to 7.0.0.

---
updated-dependencies:
- dependency-name: python-openstackclient
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -1,4 +1,4 @@
-python-openstackclient==6.6.1
+python-openstackclient==7.0.0
 python-designateclient==6.0.1
 python-heatclient==3.5.0
 python-neutronclient==11.3.1