Use python 3 in reticulate on shinyapps.io

I have some code in Python 3 which I'm running in R through the reticulate library to use in a shiny app. It works fine in my local machine, but when I published in shinyapps.io reticulate is using Python 2 by default.

So far I tried to use use_python function, but I'm not sure about the path:

use_python("/usr/bin/python3", require = TRUE)

The logs give me the error:

2019-02-12T13:44:54.691167+00:00 shinyapps[710102]: Warning: Error in initialize_python: Python shared library '/usr/lib/libpython3.5.so' not found, Python bindings not loaded.
2019-02-12T13:44:54.697101+00:00 shinyapps[710102]:   64: stop
2019-02-12T13:44:54.697103+00:00 shinyapps[710102]:   63: initialize_python
2019-02-12T13:44:54.697104+00:00 shinyapps[710102]:   62: ensure_python_initialized
2019-02-12T13:44:54.697105+00:00 shinyapps[710102]:   61: py_run_file
2019-02-12T13:44:54.697106+00:00 shinyapps[710102]:   60: source_python
2019-02-12T13:44:54.697107+00:00 shinyapps[710102]:   59: server [/srv/connect/apps/str_telefonica/app.R#57]
2019-02-12T13:44:54.697385+00:00 shinyapps[710102]: Error in initialize_python(required_module, use_environment) : 
2019-02-12T13:44:54.697387+00:00 shinyapps[710102]:   Python shared library '/usr/lib/libpython3.5.so' not found, Python bindings not loaded.