slim exporter image size

dockerfiles/exporter

@@ -3,4 +3,8 @@ FROM golang:bullseye
 # Install exporter from Golang source
 RUN go install github.com/cirocosta/monero-exporter/cmd/monero-exporter@master
 
+# Copy installed binary to fresh Ubuntu image
+FROM ubuntu:22.04
+COPY --from=OG /go/bin/monero-exporter /usr/local/bin/monero-exporter
+
 ENTRYPOINT [ "monero-exporter" ]