Build from scratch rather than debian

Dockerfile

@@ -1,14 +1,10 @@
 FROM paulcager/go-base:latest as build
 
-WORKDIR /go
-
-COPY go.mod *.go ./src/osgrid-server/
-RUN cd /go/src/osgrid-server && \
-    go install -v ./... && \
+COPY * ./
+RUN CGO_ENABLED=0 go install -v ./... && \
     sha256sum /go/bin/osgrid-server
 
-FROM debian:stable-slim
-RUN apt-get update && apt-get -y upgrade
+FROM  scratch
 WORKDIR /app
 COPY --from=build /go/bin/osgrid-server .
 EXPOSE 9090