docker buildでyarn.lockを考慮してなかったのを修正 (#6330)

Dockerfile

@@ -22,7 +22,7 @@ RUN apk add --no-cache \
     python \
     zlib-dev
 
-COPY package.json ./
+COPY package.json yarn.lock ./
 RUN yarn install
 COPY . ./
 RUN yarn build