fix build target

scripts/build.sh

@@ -76,7 +76,7 @@ read -p "Malcolm Docker images will now be built and/or pulled, force full clean
 CONFIRMATION=${CONFIRMATION:-N}
 
 # e.g., linux/amd64 or linux/arm64
-TARGET_PLATFORM=$(uname -s | tr '[:upper:]' '[:lower:]')/$(uname -m | sed 's/x86_64/amd64/' | sed 's/aarch64/arm64/')
+TARGET_PLATFORM=linux/$(uname -m | sed 's/x86_64/amd64/' | sed 's/aarch64/arm64/')
 BUILD_DATE="$(date -u +'%Y-%m-%dT%H:%M:%SZ')"
 MALCOLM_VERSION="$($GREP -P "^\s+image:.*/malcolm/" "$CONFIG_FILE" | awk '{print $2}' | cut -d':' -f2 | uniq -c | sort -nr | awk '{print $2}' | head -n 1)"
 VCS_REVISION="$(git rev-parse --short HEAD 2>/dev/null || echo unknown)"