update ngtcp2 version to v1.8.1

Signed-off-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: Zoey2936

Dockerfile

@@ -4,7 +4,7 @@ SHELL ["/bin/ash", "-eo", "pipefail", "-c"]
 ARG CURL_VERSION=curl-8_10_1
 ARG WS_VERSION=v5.7.0-stable
 ARG NGH3_VERSION=v1.6.0
-ARG NGTCP2_VERSION=v1.8.0
+ARG NGTCP2_VERSION=v1.8.1
 
 RUN apk upgrade --no-cache -a && \
     apk add --no-cache ca-certificates git build-base cmake autoconf automake coreutils libtool \