Update nginx:1.31.3 Docker digest to 5a88c9c (#2017)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

dev/nginx/Dockerfile

@@ -1,3 +1,3 @@
-FROM nginx:1.31.3@sha256:8b1903d1d65ca63882c3c567da1b77181863bbb9b2499859c7dea2b9ab3a4795
+FROM nginx:1.31.3@sha256:5a88c9c45479443d7be2eadc894b4ed0a9801bae03d97a5760ae13b5c2005942
 COPY nginx.conf /etc/nginx/nginx.conf
 COPY server.conf /etc/nginx/conf.d/default.conf