Copper6ssp Adapter: Add GVL vendor ID (#4167)

Author: AntoxaAntoxic

src/main/resources/bidder-config/copper6ssp.yaml

@@ -12,7 +12,7 @@ adapters:
         - video
         - native
       supported-vendors:
-      vendor-id: 0
+      vendor-id: 1356
     usersync:
       cookie-family-name: copper6ssp
       redirect: