Add missing sdk constriant in pubspec.yaml files. (#23124)

* Add missing sdk constriants in pubspec.yaml files.

* Update tools/android_lint/pubspec.yaml
Co-authored-by: NZachary Anderson <zanderso@users.noreply.github.com>

lib/snapshot/pubspec.yaml

@@ -3,3 +3,6 @@
 # found in the LICENSE file.
 
 # This file is needed by Fuchsia's dart_library template.
+
+environment:
+  sdk: '>=2.11.0 <3.0.0'

shell/platform/fuchsia/dart-pkg/fuchsia/pubspec.yaml

 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
+
+environment:
+  sdk: '>=2.11.0 <3.0.0'

shell/platform/fuchsia/dart-pkg/zircon/pubspec.yaml

 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
+
+environment:
+  sdk: '>=2.11.0 <3.0.0'

shell/platform/fuchsia/dart_runner/embedder/pubspec.yaml

@@ -4,3 +4,7 @@
 
 # The presence of this file is necessary in order to use the dart_library
 # template in BUILD.gn.
+
+environment:
+  sdk: '>=2.11.0 <3.0.0'
+

shell/platform/fuchsia/dart_runner/vmservice/pubspec.yaml

 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
+
+environment:
+  sdk: '>=2.11.0 <3.0.0'
+

shell/platform/fuchsia/flutter/kernel/pubspec.yaml

+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+environment:
+  sdk: '>=2.11.0 <3.0.0'

shell/platform/fuchsia/runtime/dart/profiler_symbols/pubspec.yaml

@@ -3,6 +3,8 @@
 # found in the LICENSE file.
 
 name: profiler_symbols
+environment:
+  sdk: '>=2.11.0 <3.0.0'
 version: 0
 description: Extracts a minimal symbols table for the Dart VM profiler
 author: Dart Team <misc@dartlang.org>

testing/smoke_test_failure/pubspec.yaml

 name: smoke_test_failure
+environment:
+  sdk: '>=2.11.0 <3.0.0'
 dependencies:
   test: 1.3.0
   path: 1.6.2

testing/symbols/pubspec.yaml

 name: verify_exported
+environment:
+  sdk: '>=2.11.0 <3.0.0'
 dependencies:
   path: 1.6.2
   collection: 1.14.11

tools/android_lint/pubspec.yaml

 name: android_lint
+environment:
+  sdk: '>=2.12.0-0.0.dev <3.0.0'
+
 dependencies:
   args: 1.5.0
   path: ^1.6.2

web_sdk/pubspec.yaml

 name: web_sdk_tests
 author: Flutter Authors <flutter-dev@googlegroups.com>
+environment:
+  sdk: '>=2.11.0 <3.0.0'
 
 dev_dependencies:
   analyzer: ^0.40.6