docs: update changelog about datetime rounding

Author: Yuri Zmytrakov

CHANGELOG.md

@@ -18,6 +18,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Fixed
 
+- Ensure datetime filter rounds microseconds using standard rounding instead of truncation. [#492](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/492)
+
 ## [v6.5.1] - 2025-09-30
 
 ### Fixed

stac_fastapi/tests/api/test_api.py

@@ -1631,7 +1631,7 @@ async def test_use_datetime_false(app_client, load_test_data, txn_client, monkey
 async def test_format_datetime_range_microsecond_rounding(
     app_client, txn_client, load_test_data
 ):
-    """Test that microseconds are rounded to milliseconds"""
+    """Test that microseconds are rounded in format_datetime_range"""
 
     test_collection = load_test_data("test_collection.json")
     test_collection_id = "test-collection-microseconds"