fix + edit CHANGELOG.md

Author: LiamHamsters

src/Ydb.Sdk/CHANGELOG.md

@@ -1,3 +1,4 @@
+- ADO.NET: Added `BulkUpsertAsync` for batch upsert operations with transaction checks and integration tests.
 - Optimization: On BadSession, do not invoke the `DeleteSession()` method.
 - Canceling AttachStream after calling the `DeleteSession` method.
 - Fixed bug: fixed issue where session was not deleted (`ClientTransportTimeout`).

src/Ydb.Sdk/test/Ydb.Sdk.Ado.Tests/YdbConnectionTests.cs

@@ -460,7 +460,7 @@ PRIMARY KEY (Id)
             await dropCmd.ExecuteNonQueryAsync();
         }
     }
-    
+
     [Fact]
     public async Task BulkUpsert_Throws_WhenTransactionIsOpen()
     {
@@ -500,7 +500,7 @@ PRIMARY KEY (Id)
 
         Assert.Contains("BulkUpsert cannot be used inside an active transaction", ex.Message);
 
-        await conn.CurrentTransaction.RollbackAsync();
+        await conn.CurrentTransaction?.RollbackAsync()!;
 
         await using (var dropCmd = conn.CreateCommand())
         {