Update register-scan-azure-synapse-analytics.md

Needed to update syntax to use Synapse syntax for alter role [rolename] add member [msi]

Author: mathjon248

articles/purview/register-scan-azure-synapse-analytics.md

@@ -87,7 +87,7 @@ In addition, you must also create an Azure AD user in Azure Synapse Analytics by
 CREATE USER [ServicePrincipalName] FROM EXTERNAL PROVIDER
 GO
 
-EXEC sp_addrolemember 'db_owner', [ServicePrincipalName]
+ALTER ROLE db_owner ADD MEMBER [ServicePrincipalName]
 GO
 ```