cli: fix dockerfile incorrect copy (#31883)

Author: MichaelLi65535

libs/cli/langchain_cli/project_template/Dockerfile

@@ -8,7 +8,7 @@ WORKDIR /code
 
 COPY ./pyproject.toml ./README.md ./poetry.lock* ./
 
-COPY ./package[s] ./packages
+COPY ./packages ./packages
 
 RUN poetry install  --no-interaction --no-ansi --no-root