Update Dockerfile

Better simple Dockerfile

```
$ docker build ./ -t spoof-dpi:latest
$ docker run -ti spoof-dpi:latest spoof-dpi --timeout 2000 --debug
```

Author: Viktor45

Dockerfile

@@ -1,27 +1,13 @@
-FROM golang:alpine
+FROM golang:alpine as builder
 
 WORKDIR /go
 
 RUN go install github.com/xvzc/SpoofDPI/cmd/spoof-dpi@latest
 
-ENV ADDRESS=0.0.0.0
+FROM alpine:latest
 
-ENV DNS=1.1.1.1
+WORKDIR /
 
-ENV PORT=8080
+COPY --from=builder /go/bin/spoof-dpi .
 
-ENV DEBUG=false
-
-ENV NO_BANNER=true
-
-ENV TIMEOUT=500
-
-ENV URLS=
-
-ENV PATTERN=
-
-ENV WINDOW_SIZE=0
-
-EXPOSE 8080
-
-CMD ["/bin/sh", "-c", "/go/bin/spoof-dpi -addr=${ADDRESS} -debug=${DEBUG} -dns-addr=${DNS} -port=${PORT} -no-banner=${NO_BANNER} -timeout=${TIMEOUT} -window-size=${WINDOW_SIZE} $(echo \"${URLS}\" | tr -d ' ' | tr ',' '\n' | sed -e 's/^/-url=/') -pattern ${PATTERN}"]
+ENTRYPOINT ["./spoof-dpi"]