Add service version for Caracal

We agreed by I2dd906f34118da02783bb7755e0d6c2a2b88eb5d  on the support
envelope.
Pre-RC1, we need to add a service version in the object.
Post-RC1, depending on whether it's SLURP or not SLURP, we need to bump
the minimum version or not.

This patch only focuses on pre-RC1 stage.
Given Dalmatian will be skippable, we will need a post-RC1 patch for updating the min
that will bump to Caracal.

HTH.

Change-Id: I85a37f652900affaec626aa68f5f2388139a3a87

nova/objects/service.py

@@ -262,6 +262,7 @@ SERVICE_VERSION_ALIASES = {
     'Zed': 64,
     'Antelope': 66,
     'Bobcat': 66,
+    'Caracal': 66,
 }