Update to the latest flutter candidate (#8461)

flutter-candidate.txt

diff --git a/flutter-candidate.txt b/flutter-candidate.txt
index 6a435c0..e8cf229 100644
--- a/flutter-candidate.txt
+++ b/flutter-candidate.txt
@@ -1 +1 @@
-e5cbed969cb2916bdfd1bb501e5533bef9feef64
+bcc31461856d508846f2d7b87efc9f2682f6c5b8