Prepare for the 2.11 dev SDKs (#233)

Bump the upper bound to allow 2.10 stable and 2.11.0 dev SDK versions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 84ca54c..21dba7d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## v 2.1.0-nullsafety.3
+
+* Allow 2.10 stable and 2.11.0 dev SDK versions.
+
 ## v 2.1.0-nullsafety.2
 
 * Update for the 2.10 dev sdk.
diff --git a/pubspec.yaml b/pubspec.yaml
index 37d7db0..a2c4b7b 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,11 +1,11 @@
 name: vector_math
-version: 2.1.0-nullsafety.2
+version: 2.1.0-nullsafety.3
 description: A Vector Math library for 2D and 3D applications.
 homepage: https://github.com/google/vector_math.dart
 
 environment:
   # This must remain a tight constraint until nnbd is stable
-  sdk: '>=2.10.0-0 <2.10.0'
+  sdk: '>=2.10.0-0 <2.11.0'
 
 dev_dependencies:
   benchmark_harness: any