Bump dart from cea9788 to 0c2d4bf in /auto_submit (#3691)

Bumps dart from `cea9788` to `0c2d4bf`.

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auto_submit/Dockerfile

@@ -4,7 +4,7 @@
 
 
 # Dart Docker official images can be found here: https://hub.docker.com/_/dart
-FROM dart:beta@sha256:cea97886b77255bae071d4baf5254d85b956a83c055c3e163c329ff9e87778ae
+FROM dart:beta@sha256:0c2d4bf0249b3f732945247b5be4ef2460b3c8da98762996e874744cb6cb22a9
 
 WORKDIR /app