Bump nginx from 1.25.3-alpine to 1.25.4-alpine in /build

Bumps nginx from 1.25.3-alpine to 1.25.4-alpine.

---
updated-dependencies:
- dependency-name: nginx
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

build/Dockerfile.nginx

@@ -1,5 +1,5 @@
 # syntax=docker/dockerfile:1.6
-FROM nginx:1.25.3-alpine
+FROM nginx:1.25.4-alpine
 
 ARG NJS_DIR
 ARG NGINX_CONF_DIR