Prepare to publish for stable null safety (dart-lang/source_maps#61)

pkgs/source_maps/CHANGELOG.md

diff --git a/pkgs/source_maps/CHANGELOG.md b/pkgs/source_maps/CHANGELOG.md
index 7bdead9..a59cf30 100644
--- a/pkgs/source_maps/CHANGELOG.md
+++ b/pkgs/source_maps/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.10.10
+
+* Stable release for null safety.
+
 ## 0.10.10-nullsafety.3
 
 * Update SDK constraints to `>=2.12.0-0 <3.0.0` based on beta release

pkgs/source_maps/pubspec.yaml

diff --git a/pkgs/source_maps/pubspec.yaml b/pkgs/source_maps/pubspec.yaml
index ab75dc5..648010a 100644
--- a/pkgs/source_maps/pubspec.yaml
+++ b/pkgs/source_maps/pubspec.yaml
@@ -1,5 +1,5 @@
 name: source_maps
-version: 0.10.10-nullsafety.3
+version: 0.10.10
 
 description: Library to programmatically manipulate source map files.
 homepage: https://github.com/dart-lang/source_maps
@@ -8,7 +8,7 @@
   sdk: ">=2.12.0-0 <3.0.0"
 
 dependencies:
-  source_span: '>=1.8.0-nullsafety <1.8.0'
+  source_span: ^1.8.0
 
 dev_dependencies:
   test: ^1.16.0-nullsafety