bump phoenix-api to 8.4.0

package.json

@@ -28,7 +28,7 @@
     "multiblob": "^1.5.0",
     "multicb": "^1.1.0",
     "muxrpc": "^5.0.1",
-    "phoenix-api": "~8.3.0",
+    "phoenix-api": "~8.4.0",
     "pull-pushable": "^1.1.4",
     "pull-stream": "^2.27.0",
     "scuttlebot": "^4.2.3",