replace python with python3 in docker file

Author: beachdweller

Dockerfile

@@ -16,7 +16,7 @@ COPY entrypoint.py /entrypoint.py
 COPY requirements.txt /requirements.txt
 COPY ai_tutor.py /ai_tutor.py
 
-RUN python -m pip install --upgrade pip
-RUN python -m pip install -r /requirements.txt
+RUN python3 -m pip install --upgrade pip
+RUN python3 -m pip install -r /requirements.txt
 
 ENTRYPOINT ["/entrypoint.py"]