feat: publish docker image in ci

Dockerfile

@@ -0,0 +1,10 @@
+FROM --platform=$BUILDPLATFORM golang as builder
+WORKDIR /app
+COPY . .
+RUN go mod vendor
+ARG TARGETARCH
+RUN CGO_ENABLED=0 GOARCH=$TARGETARCH go build -v -trimpath -ldflags="-w -s" .
+
+FROM scratch
+COPY --from=builder /app/wghttp /
+ENTRYPOINT ["/wghttp"]