Prepare for release 2.56.0 (#9681)

flutter-candidate.txt

diff --git a/flutter-candidate.txt b/flutter-candidate.txt
index 1efe0e0..1dcec31 100644
--- a/flutter-candidate.txt
+++ b/flutter-candidate.txt
@@ -1 +1 @@
-8034db0bd38b1c682146474cc5986e2e00dad96f
+434491ab43cf63f27cf3a5fe8bc88aba12a4971b

packages/devtools_app/lib/devtools.dart

diff --git a/packages/devtools_app/lib/devtools.dart b/packages/devtools_app/lib/devtools.dart
index 9ec9fa7..199647b 100644
--- a/packages/devtools_app/lib/devtools.dart
+++ b/packages/devtools_app/lib/devtools.dart
@@ -10,4 +10,4 @@
 /// Note: a regexp in the `dt update-version' command logic matches the constant
 /// declaration `const version =`. If you change the declaration you must also
 /// modify the regex in the `dt update-version' command logic.
-const version = '2.56.0-dev.0';
+const version = '2.56.0';

packages/devtools_app/pubspec.yaml

diff --git a/packages/devtools_app/pubspec.yaml b/packages/devtools_app/pubspec.yaml
index a5a6c65..17dbf52 100644
--- a/packages/devtools_app/pubspec.yaml
+++ b/packages/devtools_app/pubspec.yaml
@@ -7,7 +7,7 @@
 
 # Note: this version should only be updated by running the 'dt update-version'
 # command that updates the version here and in 'devtools.dart'.
-version: 2.56.0-dev.0
+version: 2.56.0
 
 repository: https://github.com/flutter/devtools/tree/master/packages/devtools_app
 

pubspec.lock

diff --git a/pubspec.lock b/pubspec.lock
index 180e37a..9a78091 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -1006,10 +1006,10 @@
     dependency: transitive
     description:
       name: web_benchmarks
-      sha256: a7dd85be82da0d52f425b830fb57838937a1bc4d8f49b3bd336fbe08fadb690b
+      sha256: "4160714bd85af6b11e7c321a2be98ec746363b69e9a496c80207c7285889960b"
       url: "https://pub.dev"
     source: hosted
-    version: "4.0.0"
+    version: "4.1.0"
   web_socket:
     dependency: transitive
     description: