Add support for @discordjs/opus (#35)

* Add @discordjs/opus as a dependency

* Update pcm test file

* Use opusscript in CI

* Use @discordjs/opus for CI

* Update README

.github/workflows/test.yml

@@ -17,5 +17,5 @@ jobs:
     - name: Install dependencies and test
       run: |
         npm install
-        npm install ffmpeg-static node-opus
+        npm install ffmpeg-static @discordjs/opus
         npm test

README.md

@@ -39,10 +39,11 @@ The following dependencies are all optional, and you should only install one fro
 each category is preferred)
 
 - Opus
-  - [`node-opus`](https://github.com/Rantanen/node-opus) (native, ^0.3.1)
-  - [`opusscript`](https://github.com/abalabahaha/opusscript) (^0.0.6)
+  - [`@discordjs/opus`](https://github.com/discordjs/opus)
+  - [`node-opus`](https://github.com/Rantanen/node-opus)
+  - [`opusscript`](https://github.com/abalabahaha/opusscript)
 - FFmpeg
-  - [`ffmpeg-static`](http://npmjs.com/ffmpeg-static) (^2.4.0)
+  - [`ffmpeg-static`](http://npmjs.com/ffmpeg-static)
   - `ffmpeg` from a [normal installation](https://www.ffmpeg.org/download.html)
 
 ## Useful Links