add RUN pip install --upgrade pip

Dockerfile

@@ -3,10 +3,13 @@ FROM python:3.9
  
 # Set the working directory to /code
 WORKDIR /code
+
+# upgrade pip
+RUN pip install --upgrade pip
  
 # Copy the current directory contents into the container at /code
 COPY ./requirements.txt /code/requirements.txt
- 
+
 # Install requirements.txt 
 RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt