Prepare to publish stable null safety release (#35)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index fe6ef82..e238b0f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 2.1.0
+
+* Stable release for null safety.
+
 ## 2.1.0-nullsafety.3
 
 * Update SDK constraints to `>=2.12.0-0 <3.0.0` based on beta release
diff --git a/pubspec.yaml b/pubspec.yaml
index d8ece2b..a7b6158 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: boolean_selector
-version: 2.1.0-nullsafety.3
+version: 2.1.0
 description: >-
   A flexible syntax for boolean expressions, based on a simplified version of
   Dart's expression syntax.
@@ -9,8 +9,8 @@
   sdk: ">=2.12.0-0 <3.0.0"
 
 dependencies:
-  source_span: '>=1.8.0-nullsafety <1.8.0'
-  string_scanner: '>=1.1.0-nullsafety <1.1.0'
+  source_span: ^1.8.0
+  string_scanner: ^1.1.0
 
 dev_dependencies:
   pedantic: ^1.10.0-nullsafety