chore(.gitignore): update .gitignore

* change .gitignore to account for nested flutter iOS build files

Change-Id: Ibd04dc0199e2d0158a5a8029e14ac4f1cc511ea2
diff --git a/.gitignore b/.gitignore
index 887d277..543c46e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,5 +5,5 @@
 .packages
 .pub/
 build/
-ios/.generated/
+**/ios/.generated/
 packages