chore: fix multi-arch build

Author: moshloop

Dockerfile

@@ -1,8 +1,7 @@
-# Multi-stage Dockerfile for dns-sync
-
-# Build stage
 FROM golang:1.23-alpine AS builder
 
+ARG TARGETARCH
+
 # Install necessary packages
 RUN apk add --no-cache git ca-certificates tzdata
 
@@ -28,6 +27,8 @@ RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build \
 # Final stage
 FROM scratch AS production
 
+ARG TARGETARCH
+
 # Import from builder
 COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
 COPY --from=builder /usr/share/zoneinfo /usr/share/zoneinfo