Updated amber to async SUnit version.

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "vendor/amber"]
 	path = vendor/amber
-	url = https://github.com/NicolasPetton/amber.git
+	url = https://github.com/herby/amber.git

vendor/amber

@@ -1 +1 @@
-Subproject commit 2504a604cb02761943e580d32e25d6c0788a1859
+Subproject commit 69feac74d95efd43ee1e9a705e1cb151e2cbdb3b