Change version of docker-compose from 2 to 2.1 for default values.

I set "http://localhost:5101/api/v1/pic/" because docker-compose doesn't allow to declare another variable such as default value

docker-compose.override.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '2.1'
 
 # The default docker-compose.override file can use the "localhost" as the external name for testing web apps within the same dev machine. 
 # The ESHOP_EXTERNAL_DNS_NAME_OR_IP environment variable is taken, by default, from the ".env" file defined like: 
@@ -23,7 +23,7 @@ services:
       - ASPNETCORE_ENVIRONMENT=Development
       - ASPNETCORE_URLS=http://0.0.0.0:80
       - ConnectionString=Server=sql.data;Database=Microsoft.eShopOnContainers.Services.CatalogDb;User Id=sa;Password=Pass@word
-      - ExternalCatalogBaseUrl=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5101    #Local: You need to open your local dev-machine firewall at range 5100-5105.  at range 5100-5105.	  
+      - PicBaseUrl=${ESHOP_AZURE_STORAGE_ACCOUNT:-http://localhost:5101/api/v1/pic/}   #Local: You need to open your local dev-machine firewall at range 5100-5105.  at range 5100-5105.	  
       - EventBusConnection=rabbitmq
     ports:
       - "5101:80"

docker-compose.vs.debug.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '2.1'
 
 services:
   basket.api:

docker-compose.vs.release.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '2.1'
 
 services:
   basket.api:

docker-compose.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '2.1'
 
 services:
   basket.api: