deps: Update Flutter to latest main, 3.19.0-9.0.pre.169

And update Flutter's supporting libraries to match.

I also ran the usual two followup commands:
  $ flutter build ios --config-only
  $ flutter build macos --config-only

and nothing changed.

Author: gnprice

pubspec.lock

@@ -664,26 +664,26 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: "78eb209deea09858f5269f5a5b02be4049535f568c07b275096836f01ea323fa"
+      sha256: cdd14e3836065a1f6302a236ec8b5f700695c803c57ae11a1c84df31e6bcf831
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.0"
+    version: "10.0.3"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
       name: leak_tracker_flutter_testing
-      sha256: b46c5e37c19120a8a01918cfaf293547f47269f7cb4b0058f21531c2465d6ef0
+      sha256: "9b2ef90589911d665277464e0482b209d39882dffaaf4ef69a3561a3354b2ebc"
       url: "https://pub.dev"
     source: hosted
-    version: "2.0.1"
+    version: "3.0.2"
   leak_tracker_testing:
     dependency: transitive
     description:
       name: leak_tracker_testing
-      sha256: a597f72a664dbd293f3bfc51f9ba69816f84dcd403cdac7066cb3f6003f3ab47
+      sha256: fd3cd66cb2bcd7b50dcd3b413af49d78051f809c8b3f6e047962765c15a0d23d
       url: "https://pub.dev"
     source: hosted
-    version: "2.0.1"
+    version: "3.0.0"
   lints:
     dependency: transitive
     description:
@@ -1290,5 +1290,5 @@ packages:
     source: hosted
     version: "3.1.2"
 sdks:
-  dart: ">=3.3.0-279.0.dev <4.0.0"
-  flutter: ">=3.18.0-19.0.pre.108"
+  dart: ">=3.4.0-71.0.dev <4.0.0"
+  flutter: ">=3.19.0-9.0.pre.169"

pubspec.yaml

@@ -24,8 +24,8 @@ environment:
   # that by the time we want to release, these will have become stable.
   # TODO: Before general release, switch to stable Flutter and Dart versions,
   #   or pin exact versions: https://github.com/zulip/zulip-flutter/issues/15
-  sdk: '>=3.3.0-279.0.dev <4.0.0'
-  flutter: '>=3.18.0-19.0.pre.108'
+  sdk: '>=3.4.0-71.0.dev <4.0.0'
+  flutter: '>=3.19.0-9.0.pre.169'
 
 # Dependencies specify other packages that your package needs in order to work.
 # To automatically upgrade your package dependencies to the latest versions