Update download-sql-server-management-studio-ssms.md

Change preview 3 to preview 4 for SSMS 19, since that preview has been released.

Author: sommarskog

docs/ssms/download-sql-server-management-studio-ssms.md

@@ -34,7 +34,7 @@ Use SSMS to query, design, and manage your databases and data warehouses, wherev
 
 ## Download SSMS
 
-To download SSMS 19 Preview 3, visit [Download SSMS 19](download-sql-server-management-studio-ssms-19.md).
+To download SSMS 19 Preview 4, visit [Download SSMS 19](download-sql-server-management-studio-ssms-19.md).
 
 :::image type="icon" source="../includes/media/download.svg" border="false":::**[Free Download for SQL Server Management Studio (SSMS) 18.12.1](https://aka.ms/ssmsfullsetup)**