build: Use debian for runtime container

Dockerfile

@@ -35,15 +35,22 @@ COPY --from=assets-builder /root/priv/static ./priv/static
 
 RUN mix do compile --force, phx.digest, release
 
-# Finally, use an Alpine container for the runtime environment
-FROM alpine:3.20.2
 
-RUN apk add --update libssl1.1 ncurses-libs bash curl dumb-init \
-  && apk upgrade \
-  && rm -rf /var/cache/apk
+
+
+
+
+# --- Set up runtime container ---
+FROM debian:bullseye-slim
+
+ENV LANG=C.UTF-8 MIX_ENV=prod REPLACE_OS_VARS=true
+
+RUN apt-get update --allow-releaseinfo-change \
+  && apt-get install --no-install-recommends --yes dumb-init ca-certificates \
+  && rm -rf /var/lib/apt/lists/*
 
 # Create non-root user
-RUN addgroup -S document_viewer && adduser -S -G document_viewer document_viewer
+RUN addgroup --system document_viewer && adduser --system --ingroup document_viewer document_viewer
 USER document_viewer
 WORKDIR /home/document_viewer