run on python3

Dockerfile

@@ -32,5 +32,5 @@ ENV LANG en_US.UTF-8
 ENV LANGUAGE en_US:en  
 ENV LC_ALL en_US.UTF-8
 
-ENTRYPOINT ["python"]
-CMD ["web_app.py"]
\ No newline at end of file
+ENTRYPOINT ["python3"]
+CMD ["web_app.py"]