ci: rename ecr repository to "highfive"

Author: pietroalbini

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
         uses: rust-lang/simpleinfra/github-actions/upload-docker-image@master
         with:
           image: highfive
-          repository: rust-highfive
+          repository: highfive
           region: us-west-1
           redeploy_ecs_cluster: rust-ecs-prod
           redeploy_ecs_service: highfive