fix(deploy): restore previous release on failure

docker-compose.yml

@@ -1,6 +1,7 @@
 services:
 
   backend:
+    image: ${BACKEND_IMAGE:-jobtracker-backend:local}
     build:
       context: .
       dockerfile: JobTrackerApi/Dockerfile
@@ -112,6 +113,7 @@ services:
       start_period: 90s
 
   frontend:
+    image: ${FRONTEND_IMAGE:-jobtracker-frontend:local}
     build:
       context: ./job-tracker-ui
       # Next's build type-checker needs more than Docker's default 64MB /dev/shm; too little