Also change the image for the second stage
The fix in fixed the build but it produces an image that could not run.
The PR fixes that as well.
Ref
@@ -17,7 +17,7 @@ RUN cargo build --$PROFILE
# ===== SECOND STAGE ======
-FROM alpine:3.8
+FROM alpine:edge
LABEL maintainer="chevdor@gmail.com"
LABEL description="This is the 2nd stage: a very small image where we copy the Substrate binary."
ARG PROFILE=release
