Try to fix missing directories errors

processing/segmenter/Dockerfile

@@ -12,28 +12,28 @@ RUN \
 
 # Drop some privileges by running as non-root user
 RUN useradd --create-home pi
-WORKDIR /home/pi/device-backend/processing/segmenter
 USER pi
 
 # Generate architecture-specific requirements.txt file to install with pip.
 # We install dependencies using pip rather than poetry because poetry tries to build numpy 1.22.4 on
 # armv7 instead of downloading from piwheels. Also, this way we don't need to have poetry in the
 # final image.
+WORKDIR /home/pi/poetry
 COPY pyproject.toml poetry.lock .
 RUN \
   PATH="$HOME/.local/bin:$PATH" pip install --no-cache-dir --extra-index-url https://www.piwheels.org/simple pip==23.3.2 && \
-  python -m venv ./poetry && \
-  ./poetry/bin/pip install --no-cache-dir --extra-index-url https://www.piwheels.org/simple poetry==1.7.1 poetry-plugin-export==1.6.0 && \
-  ./poetry/bin/poetry export -f requirements.txt -o /tmp/requirements.txt && \
+  python -m venv . && \
+  ./bin/pip install --no-cache-dir --extra-index-url https://www.piwheels.org/simple poetry==1.7.1 poetry-plugin-export==1.6.0 && \
+  ./bin/poetry export -f requirements.txt -o /tmp/requirements.txt && \
   pip freeze > ./pip-installed.txt && \
   pip uninstall -y -r ./pip-installed.txt && \
-  rm -rf ./poetry && \
-  rm ./pyproject.toml ./poetry.lock ./pip-installed.txt
+  rm -rf /home/pi/poetry
 
 # Install Python dependencies
 RUN \
   pip install --no-cache-dir --extra-index-url https://www.piwheels.org/simple -r /tmp/requirements.txt
 
 # Set up application
+WORKDIR /home/pi/device-backend/processing/segmenter
 COPY planktoscope/ main.py .
 ENTRYPOINT ["python", "main.py"]