Unify dockerfiles

Author: sauliusgrigaitis

Dockerfile

@@ -6,4 +6,4 @@ RUN scripts/build/release.sh
 FROM ubuntu:latest
 COPY --from=builder /target/compact/grandine /usr/local/bin/grandine
 
-ENTRYPOINT ["/usr/local/bin/grandine"]
+ENTRYPOINT ["grandine"]

Dockerfile.cross

@@ -1,3 +1,5 @@
 FROM --platform=$TARGETPLATFORM ubuntu:22.04
 RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates libssl-dev && apt-get clean
 COPY grandine /usr/local/bin/grandine
+
+ENTRYPOINT ["grandine"]