Bump alpine from 3.20 to 3.21 in /mongoapi/dbtestapp

Bumps alpine from 3.20 to 3.21.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

mongoapi/dbtestapp/Dockerfile

@@ -14,7 +14,7 @@ WORKDIR $GOPATH/src/dbtestapp
 COPY . .
 RUN go install
 
-FROM alpine:3.20 AS dbtestapp
+FROM alpine:3.21 AS dbtestapp
 RUN apk update && apk add -U gcompat vim strace net-tools curl netcat-openbsd bind-tools bash
 
 RUN mkdir -p /dbtestapp/bin