Bump opentracing/nginx-opentracing from nginx-1.21.5 to nginx-1.21.6 in /build (#2397)

* Bump opentracing/nginx-opentracing in /build

Bumps opentracing/nginx-opentracing from nginx-1.21.5 to nginx-1.21.6.

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

Signed-off-by: dependabot[bot] <[email protected]>

* fix alpine

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Luca Comellini <[email protected]>

Author: dependabot[bot]

build/Dockerfile

@@ -233,8 +233,8 @@ RUN --mount=type=secret,id=nginx-repo.crt,dst=/etc/ssl/nginx/nginx-repo.crt,mode
 
 
 ############################################# Base images containing libs for Opentracing #############################################
-FROM opentracing/nginx-opentracing:nginx-1.21.5 as opentracing-lib
-FROM opentracing/nginx-opentracing:nginx-1.21.5-alpine as alpine-opentracing-lib
+FROM opentracing/nginx-opentracing:nginx-1.21.6 as opentracing-lib
+FROM opentracing/nginx-opentracing:nginx-1.21.6-alpine as alpine-opentracing-lib
 
 
 ############################################# Build image for Alpine with Opentracing #############################################