➕(backend) add livekit-api dependencies

Add livekit-api dependencies. According to the documentation, this Python
package is required while issuing Access Token for a LiveKit server, to
the users.

src/backend/pyproject.toml

@@ -56,6 +56,7 @@ dependencies = [
     "WeasyPrint>=60.2",
     "whitenoise==6.6.0",
     "mozilla-django-oidc==4.0.0",
+    "livekit-api==0.5.1",
 ]
 
 [project.urls]