Update Dart beta to 2.19.0-255.2.beta

library/dart

@@ -1,12 +1,12 @@
 Maintainers: Alexander Thomas <[email protected]> (@athomas), Tony Pujals <[email protected]> (@subfuzion)
 GitRepo: https://github.com/dart-lang/dart-docker.git
 GitFetch: refs/heads/main
-GitCommit: b34021c5bd18c3b37456851d6b57635c78b5c5bf
+GitCommit: 5c46679ae6d2957bb38e66f29ce6929a02d368d4
 
 Tags: 2.18.2-sdk, 2.18-sdk, 2-sdk, stable-sdk, sdk, 2.18.2, 2.18, 2, stable, latest
 Architectures: amd64, arm32v7, arm64v8
 Directory: stable/bullseye
 
-Tags: 2.19.0-146.2.beta-sdk, beta-sdk, 2.19.0-146.2.beta, beta
+Tags: 2.19.0-255.2.beta-sdk, beta-sdk, 2.19.0-255.2.beta, beta
 Architectures: amd64, arm32v7, arm64v8
 Directory: beta/bullseye