minor correction

nominatim-3.5/Dockerfile

@@ -27,7 +27,6 @@ RUN echo "host all  all    0.0.0.0/0  trust" >> /etc/postgresql/12/main/pg_hba.c
     echo "listen_addresses='*'" >> /etc/postgresql/12/main/postgresql.conf
 
 # Osmium install to run continuous updates
-RUN pip install --upgrade pip
 RUN pip3 install osmium
 
 # Nominatim install