cosmos: update changelog for 0.25.0 release (#2799)

Author: analogrelay

sdk/cosmos/azure_data_cosmos/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Release History
 
-## 0.25.0 (Unreleased)
+## 0.25.0 (2025-08-05)
 
 ### Features Added
 * Added `if_match_etag` to `ItemOptions` ([#2705](https://github.com/Azure/azure-sdk-for-rust/pull/2705))
@@ -10,10 +10,6 @@
 
 - Minimum supported Rust version (MSRV) is now 1.85.
 
-### Bugs Fixed
-
-### Other Changes
-
 ## 0.24.0 (2025-06-10)
 
 ### Features Added