Update the path of poetry files in Dockerfiles

docker/Dockerfile

@@ -25,7 +25,7 @@ RUN apt-get update \
  && apt-get clean
 
 WORKDIR /tmp
-COPY pyproject.toml /tmp/
+COPY backend/pyproject.toml backend/poetry.lock /tmp/
 
 # hadolint ignore=DL3013
 RUN pip install --upgrade pip \

docker/Dockerfile.prod

@@ -11,7 +11,7 @@ ENV PYTHONUNBUFFERED 1
 RUN groupadd -g 61000 doccano \
   && useradd -g 61000 -l -M -s /bin/false -u 61000 doccano
 
-COPY --chown=doccano:doccano pyproject.toml poetry.lock /backend/
+COPY --chown=doccano:doccano backend/pyproject.toml backend/poetry.lock /backend/
 
 # hadolint ignore=DL3013
 RUN apt-get update \