Fix link to Tor proxy library in BUILD
We use the ACINQ fork instead of the thaliproject original project.
Phoenix uses a library to manage the communication with the tor binary. This library must be built locally
-1. Clone the library from https://github.com/thaliproject/Tor_Onion_Proxy_Library
+1. Clone the library from https://github.com/ACINQ/Tor_Onion_Proxy_Library
2. At the root of this project, run:
```shell
./gradlew install
