Upgrade libasync and memutils dependencies.

frameworks/D/vibed/dub.selections.json

@@ -1,11 +1,11 @@
 {
 	"fileVersion": 1,
 	"versions": {
-		"memutils": "0.4.3",
+		"memutils": "0.4.4",
 		"vibe-d": "0.7.27",
 		"libevent": "2.0.1+2.0.16",
 		"openssl": "1.1.4+1.0.1g",
-		"libasync": "0.7.5",
+		"libasync": "0.7.8",
 		"libev": "5.0.0+4.04"
 	}
 }