Bump dart from `e5138f8` to `7617ecb` in /auto_submit (#2445)

Bumps dart from `e5138f8` to `7617ecb`.

---
updated-dependencies:
- dependency-name: dart
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
diff --git a/auto_submit/Dockerfile b/auto_submit/Dockerfile
index c0265d7..af3b0c1 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:e5138f86e843c181278aeb26a992901b5e3751e6261a01b28d1b57276beed718
+FROM dart:beta@sha256:7b1b5c83b549a6410a3f89a54ec3f702ec0cbe6ac5e8fc02b1bdc0970a6cba73
 
 WORKDIR /app