bump alpine version to 3.20 to custom-error-pages (#11530)

Author: owngr

images/custom-error-pages/rootfs/Dockerfile

@@ -14,7 +14,7 @@
 
 ARG GOLANG_VERSION
 
-FROM golang:${GOLANG_VERSION}-alpine3.18 as builder
+FROM golang:${GOLANG_VERSION}-alpine3.20 as builder
 
 RUN apk update \
     && apk upgrade && apk add git
@@ -37,4 +37,4 @@ COPY --from=builder /go/src/k8s.io/ingress-nginx/images/custom-error-pages/www /
 COPY --from=builder /go/src/k8s.io/ingress-nginx/images/custom-error-pages/etc /etc
 USER nonroot:nonroot
 
-CMD ["/nginx-errors"]
+CMD ["/nginx-errors"]