Bump dart from `30569f8` to `5a7d604` in /auto_submit (#2660)

Bumps dart from `30569f8` to `5a7d604`.

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diff --git a/auto_submit/Dockerfile b/auto_submit/Dockerfile
index 4f26356..125c81f 100644
--- a/auto_submit/Dockerfile
+++ b/auto_submit/Dockerfile
@@ -4,7 +4,7 @@
 
 
 # Dart Docker official images can be found here: https://hub.docker.com/_/dart
-FROM dart:beta@sha256:30569f8578d1bb5d2f1992494bba7739bda3d2904d3c512ef985ecf7cc1508be
+FROM dart:beta@sha256:5a7d604539a878742ffef3da2726e5245c5b1834dc569881debe5fe64a6ac767
 
 WORKDIR /app