set alpine version

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:20231219 AS builder
+FROM alpine:3.19.1 AS builder
 ARG MDNS_REPEATER_VERSION=local
 WORKDIR /
 COPY mdns-repeater.c mdns-repeater.c
@@ -7,7 +7,7 @@ RUN set -ex && \
     apk add --no-cache build-base && \
     gcc -o /bin/mdns-repeater mdns-repeater.c -DMDNS_REPEATER_VERSION=\"${MDNS_REPEATER_VERSION}\"
 
-FROM alpine:20231219
+FROM alpine:3.19.1
 # hadolint ignore=DL3018
 RUN set -ex && \
     apk add --no-cache vlan libcap bash