docker: Fix amd base

Author: enwask

docker/Dockerfile.amd

@@ -6,12 +6,13 @@
 ARG ROCM_VERSION=6.3.2
 ARG base=ubuntu:22.04
 
+FROM $base AS ubuntu-base
 FROM rocm/dev-ubuntu-22.04:${ROCM_VERSION}-complete AS sdk-base
 
 ENV DEBIAN_FRONTEND=noninteractive
 
 # Base may be specified with the nogil base image to provide Python
-COPY --from=$base /opt /opt
+COPY --from=ubuntu-base /opt /opt
 ENV PATH="/opt/python3/bin:${PATH}"
 
 ARG UCX_BRANCH="v1.16.0"