Update nginx Docker tag to v1.28.0

| datasource | package | from   | to     |
| ---------- | ------- | ------ | ------ |
| docker     | nginx   | 1.27.5 | 1.28.0 |


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

Author: renovate[bot]

build/Dockerfile.nginx

@@ -1,5 +1,5 @@
 # syntax=docker/dockerfile:1.15
-FROM nginx:1.27.5-alpine-otel
+FROM nginx:1.28.0-alpine-otel
 
 ARG NJS_DIR
 ARG NGINX_CONF_DIR