kilo: release oslo.db 1.7.4

Changes:

user@xubuntu:~/git/oslo.db$ git log --oneline --no-merges 1.7.3..
ae22f7f Fix tests to work under both pymsysql 0.6.2 and 0.7.x
a45e825 Add testtools to requirements.txt

This is needed to get ceilometer installing in kilo again.

Change-Id: Ib318bea32e6178997b888246663df193c896813e
Closes-Bug: #1555721

deliverables/kilo/oslo.db.yaml

@@ -44,3 +44,9 @@ releases:
         hash: c5f468d8fb237842aad54e5fdebd35a8be19df51
     highlights: >
         Dependency updates (caps synced from stable/kilo global-requirements).
+  - version: 1.7.4
+    projects:
+      - repo: openstack/oslo.db
+        hash: 974fc94a623956a5f7bf60b93d2de65259af8068
+    highlights: >
+        Dependency updates to fix bug 1555721.