New Dart favicon (#1690)

* New Dart favicon

Fixes #1689
diff --git a/lib/resources/favicon.png b/lib/resources/favicon.png
index baaffdd..09e78c9 100644
--- a/lib/resources/favicon.png
+++ b/lib/resources/favicon.png
Binary files differ
diff --git a/testing/test_package_docs/static-assets/favicon.png b/testing/test_package_docs/static-assets/favicon.png
index baaffdd..09e78c9 100644
--- a/testing/test_package_docs/static-assets/favicon.png
+++ b/testing/test_package_docs/static-assets/favicon.png
Binary files differ