ci: use build matrix rather than separate jobs

Dockerfile.debian

@@ -0,0 +1,38 @@
+FROM nginxproxy/docker-gen:0.11.0-debian AS docker-gen
+
+FROM nginxproxy/forego:0.17.2-debian AS forego
+
+# Build the final image
+FROM nginx:1.25.3
+
+ARG NGINX_PROXY_VERSION
+# Add DOCKER_GEN_VERSION environment variable because 
+# acme-companion rely on it (but the actual value is not important)
+ARG DOCKER_GEN_VERSION="unknown"
+ENV NGINX_PROXY_VERSION=${NGINX_PROXY_VERSION} \
+   DOCKER_GEN_VERSION=${DOCKER_GEN_VERSION} \
+   DOCKER_HOST=unix:///tmp/docker.sock
+
+# Install/update certificates
+RUN apt-get update \
+   && apt-get install -y -q --no-install-recommends ca-certificates \
+   && apt-get clean \
+   && rm -r /var/lib/apt/lists/*
+
+# Configure Nginx
+RUN echo "daemon off;" >> /etc/nginx/nginx.conf \
+   && sed -i 's/worker_processes  1/worker_processes  auto/' /etc/nginx/nginx.conf \
+   && sed -i 's/worker_connections  1024/worker_connections  10240/' /etc/nginx/nginx.conf \
+   && mkdir -p '/etc/nginx/dhparam'
+
+# Install Forego + docker-gen
+COPY --from=forego /usr/local/bin/forego /usr/local/bin/forego
+COPY --from=docker-gen /usr/local/bin/docker-gen /usr/local/bin/docker-gen
+
+COPY network_internal.conf /etc/nginx/
+
+COPY app nginx.tmpl LICENSE /app/
+WORKDIR /app/
+
+ENTRYPOINT ["/app/docker-entrypoint.sh"]
+CMD ["forego", "start", "-r"]