Flutter version bump (#506)

diff --git a/Dockerfile b/Dockerfile
index ca4b02c..7f4e00b 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -6,7 +6,7 @@
 # To retrieve this value, please run the following in your closest shell:
 #
 # $ (cd flutter && git rev-parse HEAD)
-ARG FLUTTER_COMMIT=8f7327f83a3e094285163ae402c6f94190fc1674
+ARG FLUTTER_COMMIT=7f56b53de4e5da2147c4d30d857a72c6f2e4f42f
 
 # We install unzip and remove the apt-index again to keep the
 # docker image diff small.
diff --git a/flutter b/flutter
index 8f7327f..7f56b53 160000
--- a/flutter
+++ b/flutter
@@ -1 +1 @@
-Subproject commit 8f7327f83a3e094285163ae402c6f94190fc1674
+Subproject commit 7f56b53de4e5da2147c4d30d857a72c6f2e4f42f