Bump version number for release

Bump version number for release to 4.0.0-nullsafety.3
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ec218d..1dd1bde 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,9 +1,13 @@
 # Change Log for `process_runner`
 
-## 4.0.0-nullsafety.2
+## 4.0.0-nullsafety.3
 
 * Rebase onto non-nullsafety version 3.1.1 to pick up those changes. 
 
+## 4.0.0-nullsafety.2
+
+* Rebase onto non-nullsafety version 3.1.0 to pick up those changes. 
+
 ## 4.0.0-nullsafety.1
 
 * Expand the sdk constraint to `<2.11.0`.
diff --git a/pubspec.yaml b/pubspec.yaml
index 56e522c..dcf2682 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -3,7 +3,7 @@
 # found in the LICENSE file.
 
 name: process_runner
-version: 4.0.0-nullsafety.2
+version: 4.0.0-nullsafety.3
 description: A process invocation astraction for Dart that manages a multiprocess queue.
 homepage: https://github.com/google/process_runner