fix: Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN12-SYSTEMD-6277507
- https://snyk.io/vuln/SNYK-DEBIAN12-SYSTEMD-6277507
- https://snyk.io/vuln/SNYK-DEBIAN12-ZLIB-6008963
- https://snyk.io/vuln/SNYK-DEBIAN12-GNUTLS28-6474581
- https://snyk.io/vuln/SNYK-DEBIAN12-SYSTEMD-6277509

Dockerfile

@@ -1,11 +1,11 @@
-FROM debian:bookworm as stage
+FROM debian:12.6 as stage
 ARG PACKAGE_BASEURL=https://download.zerotier.com/debian/bookworm/pool/main/z/zerotier-one
 ARG ARCH=amd64
 ARG VERSION=1.12.2
 RUN apt-get update -qq && apt-get install -qq --no-install-recommends -y ca-certificates curl
 RUN curl -sSL -o zerotier-one.deb "${PACKAGE_BASEURL}/zerotier-one_${VERSION}_${ARCH}.deb"
 
-FROM debian:bookworm
+FROM debian:12.6
 RUN mkdir /app
 WORKDIR /app
 COPY --from=stage zerotier-one.deb .