Fixed dockerfile for correct run with bash

Dockerfile

@@ -10,8 +10,7 @@ COPY ./requirements.txt /code/requirements.txt
 RUN pip install --no-cache-dir --upgrade pip
 
 RUN --mount=type=secret,id=PIPLOC,mode=0444,required=true \
-  PIPLOC=$(cat /run/secrets/PIPLOC) \
-  pip install --no-cache-dir ${PIPLOC}
+bash -c "PIPLOC=$(cat /run/secrets/PIPLOC); pip install --no-cache-dir \${PIPLOC}"
 
 RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt