=docker Fix 5.7 docker image name (#974)

Author: ktoso

docker/docker-compose.2004.57.yaml

@@ -3,31 +3,31 @@ version: "3"
 services:
 
   runtime-setup:
-    image: swift-distributed-actors:20.04-main
+    image: swift-distributed-actors:20.04-57
     build:
       args:
         base_image: "swiftlang/swift:nightly-5.7-focal"
 
   unit-tests:
-    image: swift-distributed-actors:20.04-main
+    image: swift-distributed-actors:20.04-57
 
   unit-tests-until-failure:
-    image: swift-distributed-actors:20.04-main
+    image: swift-distributed-actors:20.04-57
 
   integration-tests:
-    image: swift-distributed-actors:20.04-main
+    image: swift-distributed-actors:20.04-57
 
   test:
-    image: swift-distributed-actors:20.04-main
+    image: swift-distributed-actors:20.04-57
 
   bench:
-    image: swift-distributed-actors:20.04-main
+    image: swift-distributed-actors:20.04-57
 
   shell:
-    image: swift-distributed-actors:20.04-main
+    image: swift-distributed-actors:20.04-57
 
   sample-crash:
-    image: swift-distributed-actors:20.04-main
+    image: swift-distributed-actors:20.04-57
 
   sample-crash-actor:
-    image: swift-distributed-actors:20.04-main
+    image: swift-distributed-actors:20.04-57