Update alpine Docker tag to v3.18.3

Dockerfile

@@ -19,7 +19,7 @@ COPY mutatingwebhook.go .
 RUN go install .
 
 # production image ############################################
-FROM alpine:3.18.2@sha256:82d1e9d7ed48a7523bdebc18cf6290bdb97b82302a8a9c27d4fe885949ea94d1 AS prod
+FROM alpine:3.18.3@sha256:7144f7bab3d4c2648d7e59409f15ec52a18006a128c733fcff20d3a4a54ba44a AS prod
 RUN apk add --no-cache ca-certificates
 
 COPY --from=build-env /go/bin/network-health-admission-controller /bin/admission-controller