Update SDK version constraint in dart_internal

Required for further increasing of version main branch.

Change-Id: I8454ca16c6a4d6d9f9e0cef1537515c731d181c7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/449804
Commit-Queue: Bob Nystrom <[email protected]>
Auto-Submit: Ivan Inozemtsev <[email protected]>
Reviewed-by: Bob Nystrom <[email protected]>

Author: iinozemtsev

pkg/dart_internal/pubspec.yaml

@@ -9,7 +9,7 @@ repository: https://github.com/dart-lang/sdk/tree/main/pkg/dart_internal
 environment:
   # Restrict the upper bound so that we can remove support for this in a later
   # version of the SDK without it being a breaking change.
-  sdk: '>=3.5.0 <3.11.0'
+  sdk: '>=3.5.0 <3.12.0'
 
 resolution: workspace