Add docker build

Dockerfile

@@ -0,0 +1,17 @@
+FROM golang:latest AS builder
+
+COPY . /fetcher
+
+WORKDIR /fetcher
+
+ENV CGO_ENABLED=0
+
+RUN go build -o /usr/local/bin/fetcher
+
+FROM alpine:latest
+
+COPY --from=builder /usr/local/bin/fetcher /usr/local/bin/fetcher
+
+RUN apk update && apk add ca-certificates
+
+USER nobody