include TRANSLATIONS_DIR as environment variable in the Docker image

Dockerfile

@@ -18,6 +18,8 @@ EXPOSE 8080
 # The app reads the configuration from this location.
 # No need to set environment variables in your docker-compose.
 ENV OSS_PARAMS_FILENAME=/etc/gso/config.json
+# Set the environment variable for the translations directory
+ENV TRANSLATIONS_DIR=$(python3 -c "from os import path; import gso; print(path.join(path.split(gso.__file__)[0], 'translations'))" | tail -n 1)
 
 # Start the FastAPI application
 CMD ["uvicorn", "gso.main:app", "--host", "0.0.0.0", "--port", "8080"]