simplify updated pip to one line in dockerfile

Author: jlchang

Dockerfile

@@ -22,7 +22,6 @@ RUN apt-get -y update && \
   apt -y install python3.7 && \
   apt -y install python3.7-dev
 
-RUN python3.7 -m pip install pip
 RUN python3.7 -m pip install --upgrade pip
 
 # Set cleaner defaults (`alias` fails)