Release python-neutronclient for Xena-1 milestone

This is a library release for ospython-neutronclient for the Xena-1
milestone. This repo includes commits that have not been releases for
this cycle yet.

If the team is ready to process with this release, please leave a +1
to indicate we should go ahead with the release.

If the team needs more time for things about to merge, or if there is
some other reason a release should not be done at this time, please
leave a -1 with a comment indicating the status. Then update the patch
with the new commit hash to use once the team is ready to do the
release.

$ git log --oneline --no-merges 7.3.0..10227b6
10227b6 setup.cfg: Replace dashes with underscores
2c2a1f4 Replace getargspec with getfullargspec
d87683b Fix lower constraints
f3756a3 Add Python3 xena unit tests
1237376 Update master for stable/wallaby
3140fe0 Support passing mTLS certificate/key to HTTPClient

Signed-off-by: Hervé Beraud <hberaud@redhat.com>
Change-Id: Ib81ce3bae5c68d1d61b2a16b43f746e3d8e08b5a

deliverables/xena/python-neutronclient.yaml

@@ -6,3 +6,8 @@ team: neutron
 type: client-library
 repository-settings:
   openstack/python-neutronclient: {}
+releases:
+  - version: 7.4.0
+    projects:
+      - repo: openstack/python-neutronclient
+        hash: 10227b681f546ef126b8f4ef2e9488c8a1a9f0c0