Use the correct base url for latest yml

Co-authored-by: Fabian Fett <[email protected]>

Author: shahmishal

nightly-main/amazonlinux/2/buildx/Dockerfile

@@ -46,7 +46,7 @@ FROM base-$TARGETARCH AS final
 ARG OS_VER=$SWIFT_PLATFORM$OS_MAJOR_VER$OS_ARCH_SUFFIX
 ARG PLATFORM_WEBROOT="$SWIFT_WEBROOT/$SWIFT_PLATFORM$OS_MAJOR_VER$OS_ARCH_SUFFIX"
 
-RUN echo "${SWIFT_WEBROOT}/latest-build.yml"
+RUN echo "${PLATFORM_WEBROOT}/latest-build.yml"
 
 RUN set -e; \
     # - Latest Toolchain info