chore: use ooni/[email protected]

This is the latest alpha release as of this writing and contains
the necessary code to run riseupvpn as a default-disable experimental
nettest. As documented by ooni/probe#2576,
this release also has an issue when running that we'll fix on the
probe-cli side as soon as possible.

package.json

@@ -4,7 +4,7 @@
   "author": "Open Observatory of Network Interference (OONI) <[email protected]>",
   "productName": "OONI Probe",
   "version": "3.9.1",
-  "probeVersion": "3.17.5",
+  "probeVersion": "3.19.0-alpha.4",
   "main": "main/index.js",
   "license": "BSD-3-Clause",
   "repository": "ooni/probe-desktop",