CodeGen from PR 19661 in Azure/azure-rest-api-specs

(PostgreSQL) fixes Azure/azure-sdk-for-go#18506 (#19661)

Azure is offering postgres 14 flexible server but the sdk is currently limited to Versions 11 12 and 13.

https://github.com/Azure/azure-sdk-for-go/blob/sdk/resourcemanager/postgresql/armpostgresqlflexibleservers/v1.0.0/sdk/resourcemanager/postgresql/armpostgresqlflexibleservers/zz_generated_constants.go#L263

fixes Azure/azure-sdk-for-go#18506

Author: SDKAuto

schemas/2021-06-01/Microsoft.DBforPostgreSQL.json

@@ -613,6 +613,7 @@
             {
               "type": "string",
               "enum": [
+                "14",
                 "13",
                 "12",
                 "11"