Update alpine Docker tag to v3.18.5

Dockerfile

@@ -21,7 +21,7 @@ COPY mutatingwebhook.go .
 RUN go install .
 
 # production image ############################################
-FROM alpine:3.18.4@sha256:eece025e432126ce23f223450a0326fbebde39cdf496a85d8c016293fc851978 AS prod
+FROM alpine:3.18.5@sha256:34871e7290500828b39e22294660bee86d966bc0017544e848dd9a255cdf59e0 AS prod
 RUN apk add --no-cache ca-certificates
 
 COPY --from=build-env /go/bin/ingress-waf-admission-controller /bin/admission-controller