Update Dockerfile

Author: AlfHou

Dockerfile

@@ -12,7 +12,8 @@ RUN go build -o ./app ./main.go
 FROM node:16-alpine as build-stage
 WORKDIR /app
 COPY ./ui/package*.json ./
-RUN apk add --no-cache autoconf automake build-base nasm libc6-compat python3 py3-pip make g++ libpng-dev zlib-dev
+RUN apk add --no-cache autoconf automake build-base nasm libc6-compat python3 py3-pip make g++ libpng-dev zlib-dev pngquant
+
 RUN npm install
 COPY ./ui .
 RUN npm run build