Update api-version-retirement-sep-2023.md

Update min API version in portal

Author: dlepow

articles/api-management/breaking-changes/api-version-retirement-sep-2023.md

@@ -56,7 +56,7 @@ We also recommend setting the **Minimum API version** in your API Management ins
 
 ### Update Minimum API version setting on your API Management instance
 
-We recommend setting the **Minimum API version** for your API Management instance using the Azure portal. This setting limits control plane API calls to your instance with an API version equal to or newer than this value. Currently you can set this to **2019-12-01**.
+We recommend setting the **Minimum API version** for your API Management instance using the Azure portal. This setting limits control plane API calls to your instance with an API version equal to or newer than this value. Currently you can set this to **2021-08-01**.
 
 To set the **Minimum API version** in the portal: