[Cosmos] Release: azcosmos 1.6.0-beta.3 (#27494)

* Release azcosmos 1.6.0-beta.3

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 041770fb-e6ee-45ef-9c8e-5f527718a2a4

* Release: refresh azcosmos 1.6.0-beta.3 changelog

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 041770fb-e6ee-45ef-9c8e-5f527718a2a4

* Trigger PR validation

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 041770fb-e6ee-45ef-9c8e-5f527718a2a4

---------

Copilot-Session: 041770fb-e6ee-45ef-9c8e-5f527718a2a4

Author: tvaron3

sdk/data/azcosmos/CHANGELOG.md

@@ -2,18 +2,12 @@
 
 <!-- cSpell:ignore documentdb unmarshalling -->
 
-## 1.6.0-beta.3 (Unreleased)
-
-### Features Added
-
-### Breaking Changes
+## 1.6.0-beta.3 (2026-09-01)
 
 ### Bugs Fixed
 
 * Fixed `ReadManyItems` requests that target a single logical partition key to include that key in service telemetry, allowing `CDBPartitionKeyRUConsumption` to attribute the request charge to the partition. See [PR 27491](https://github.com/Azure/azure-sdk-for-go/pull/27491).
 
-### Other Changes
-
 ## 1.6.0-beta.2 (2026-08-03)
 
 ### Bugs Fixed