Fixed missing equal sign

Author: rofrano

Dockerfile

@@ -24,6 +24,6 @@ ENV FLASK_APP=wsgi:app
 ENV PORT=8080
 EXPOSE $PORT
 
-ENV GUNICORN_BIND 0.0.0.0:$PORT
+ENV GUNICORN_BIND=0.0.0.0:$PORT
 ENTRYPOINT ["gunicorn"]
 CMD ["--log-level=info", "wsgi:app"]