Pip upgrade

Hello people,
Recently I started to get the following message every time I reboot the app (https://share.streamlit.io/larryprato/covid_dashboard/main/covid_dashboard.py):
“WARNING: You are using pip version 21.0.1; however, version 21.1.1 is available.
You should consider upgrading via the ‘/home/appuser/venv/bin/python -m pip install --upgrade pip’ command.”

I don’t know how to proceed to do such upgrade. As a consequence the format text had changed in some titles and charts.
Waht can I do? Where should I do that update?
Please, someone who can give me a hand in that issue.

Larry