add ssl certs to scratch image (#171)

Dockerfile

@@ -15,12 +15,15 @@ RUN go get -d -v
 RUN CGO_ENABLED=0 GOOS=linux GOARCH=${TARGETARCH} go build \
     -ldflags="-X 'github.com/jonasvinther/medusa/cmd.Version=${VERSION}'" \
     -o /go/bin/medusa
+RUN apk add ca-certificates && update-ca-certificates
 
 RUN adduser -S scratchuser
 RUN chown scratchuser /go/bin/medusa
 
 FROM scratch
 COPY --from=builder /go/bin/medusa /medusa
 COPY --from=builder /etc/passwd /etc/passwd
+COPY --from=builder /usr/share/ca-certificates/mozilla/* /etc/ssl/certs/
+
 USER scratchuser
 ENTRYPOINT ["/medusa"]