fix: set version info for Docker image

Dockerfile

@@ -2,8 +2,9 @@ FROM node:16 as builder
 
 WORKDIR /build
 COPY ./web .
+COPY ./VERSION .
 RUN npm install
-RUN npm run build
+RUN REACT_APP_VERSION=$(cat VERSION) npm run build
 
 FROM golang AS builder2
 
@@ -15,7 +16,7 @@ WORKDIR /build
 COPY . .
 COPY --from=builder /build/build ./web/build
 RUN go mod download
-RUN go build -ldflags "-s -w -extldflags '-static'" -o message-pusher
+RUN go build -ldflags "-s -w -X 'gin-template/common.Version=$(cat VERSION)' -extldflags '-static'" -o message-pusher
 
 FROM alpine