Release debtcollector 2.0.0

This version officially drop the python 2 support so we release a major
version of debtcollector to inform user that we break
the backward compatibility.

OpenStack is dropping the py2.7 support in ussuri cycle.

Complete discussion & schedule can be found in
-
http://lists.openstack.org/pipermail/openstack-discuss/2019-October/010142.html
- https://etherpad.openstack.org/p/drop-python2-support

Ussuri Communtiy-wide goal:
https://governance.openstack.org/tc/goals/selected/ussuri/drop-py27.html

Change-Id: If00536f6182ac198a0e0d6ea36dfdc31c27655ab

deliverables/ussuri/debtcollector.yaml

@@ -6,3 +6,8 @@ team: oslo
 type: library
 repository-settings:
   openstack/debtcollector: {}
+releases:
+  - version: 2.0.0
+    projects:
+      - repo: openstack/debtcollector
+        hash: 3e241f33da72a3a5139a37545e6b8ab6a82bccdf