Bump dart from `9fa6436` to `673bde0` in /auto_submit (#2304)

Bumps dart from `9fa6436` to `673bde0`.

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

Signed-off-by: dependabot[bot] <support@github.com>

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 7b836dd..074ba87 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@sha256:9fa643606ff56e8837b342f4300e360267de82a0a6cc5e5ed265120aa1a5aa30
+FROM dart:beta@sha256:673bde0d1eb1c357d2953b8342e395bd63648f9878e10a833fd0b1780896fe76
 
 WORKDIR /app