Add missing dependency on pkg/typed_data (#39)

diff --git a/pubspec.yaml b/pubspec.yaml
index 4d71cb1..a0e1343 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -8,5 +8,6 @@
 dependencies:
   collection: '^1.0.0'
   convert: '>=1.0.0 <3.0.0'
+  typed_data: '^1.0.0'
 dev_dependencies:
   test: '^0.12.17'