Release protobuf-5.1.0 (#1078)

diff --git a/protobuf/CHANGELOG.md b/protobuf/CHANGELOG.md
index 9d5c038..76d6737 100644
--- a/protobuf/CHANGELOG.md
+++ b/protobuf/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 5.1.0-wip
+## 5.1.0
 
 * Update default size limit of `CodedBufferReader` from 67,108,864 bytes to
   2,147,483,647 bytes, and default recursion limit from 64 to 100.
diff --git a/protobuf/pubspec.yaml b/protobuf/pubspec.yaml
index 84b70d0..efd8781 100644
--- a/protobuf/pubspec.yaml
+++ b/protobuf/pubspec.yaml
@@ -1,5 +1,5 @@
 name: protobuf
-version: 5.1.0-wip
+version: 5.1.0
 description: >-
   Runtime library for protocol buffers support. Use with package:protoc_plugin
   to generate Dart code for your '.proto' files.