Update Dockerfile to include PYTHONPATH for tests

Dockerfile

@@ -1,6 +1,9 @@
 FROM python:3.11-slim as base
 
-WORKDIR /app
+ENV APP_BASE_PATH="/app"
+ENV APP_SRC_PATH=${APP_BASE_PATH}/src
+ENV PYTHONPATH="${APP_SRC_PATH}:${PYTHONPATH}"
+WORKDIR $APP_BASE_PATH
 
 RUN apt-get update && apt-get install -y \
     build-essential \
@@ -23,12 +26,12 @@ HEALTHCHECK CMD curl --fail http://localhost:8501/_stcore/health
 ENTRYPOINT ["./start.sh"]
 
 FROM pip-service as service
-WORKDIR /app/src
+WORKDIR $APP_SRC_PATH
 COPY ./src .
 
 FROM service-setup as development
-WORKDIR /app
+WORKDIR $APP_BASE_PATH
 COPY ./dev-requirements.txt .
 RUN pip3 install -r dev-requirements.txt
 
-WORKDIR /app/src
+WORKDIR $APP_SRC_PATH