use specific apline image version so the iptables will be installed w…

…ith version 1.8.9 instead of 1.8.10 (netbirdio#1405)

client/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3
+FROM alpine:3.18.5
 RUN apk add --no-cache ca-certificates iptables ip6tables
 ENV NB_FOREGROUND_MODE=true
 ENTRYPOINT [ "/go/bin/netbird","up"]