我试图为我的Gatsby应用程序构建我的 Docker 映像。每当我运行命令docker build . -t gatsbyapp时，它都会给我一个错误：

failed to solve with frontend dockerfile.v0: failed to build LLB:
failed to compute cache key: "/.env" not found: not found

同时我的 Dockerfile 如下所示：

FROM node:13

WORKDIR /app

COPY package.json .

RUN yarn global add gatsby-cli

RUN yarn install

COPY gatsby-config.js .

COPY .env .

EXPOSE 8000

CMD ["gatsby","develop","-H","0.0.0.0"]