Release oslo.serialization 5.2.1 for 2023.2 (Bobcat)

$ git log --oneline --no-merges 5.2.0..47ea1d79
47ea1d7 (HEAD -> stable/2023.2, origin/stable/2023.2) [jsonutils] Add handling of datetime.date format
e23100f (gerrit/stable/2023.2) Update TOX_CONSTRAINTS_FILE for stable/2023.2
d1c057d Update .gitreview for stable/2023.2

Change-Id: I68ef0796d10e33fa067b9dc4601dc63d647bc996

deliverables/bobcat/oslo.serialization.yaml

@@ -11,6 +11,10 @@ releases:
     projects:
       - repo: openstack/oslo.serialization
         hash: a0ba2d777cc3f96354bf3deab09a5b71a0f37b0a
+  - version: 5.2.1
+    projects:
+      - repo: openstack/oslo.serialization
+        hash: 47ea1d798175833e3e2de49b8c338f384e318fb3
 branches:
   - name: stable/2023.2
     location: 5.2.0