Update pubspec.yaml

Co-authored-by: Jacob MacDonald <jakemac@google.com>
diff --git a/pubspec.yaml b/pubspec.yaml
index ab5f4b4..c6efeb2 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -6,3 +6,6 @@
 
 environment:
   sdk: '>=2.1.1 <3.0.0'
+
+dependencies:
+  meta: ^1.2.2