Bump opentracing/nginx-opentracing in /build

Bumps opentracing/nginx-opentracing from nginx-1.21.3 to nginx-1.21.4.

---
updated-dependencies:
- dependency-name: opentracing/nginx-opentracing
  dependency-type: direct:production
...

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

build/Dockerfile

@@ -162,7 +162,7 @@ RUN --mount=type=secret,id=nginx-repo.crt,dst=/etc/ssl/nginx/nginx-repo.crt,mode
 
 
 ############################################# Base image containing libs for Opentracing #############################################
-FROM opentracing/nginx-opentracing:nginx-1.21.3 as opentracing-lib
+FROM opentracing/nginx-opentracing:nginx-1.21.4 as opentracing-lib
 
 
 ############################################# Build image for Opentracing #############################################