Bump nats

Bumps nats from 2.10.17 to 2.10.21.

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

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

Author: dependabot[bot]

tests/tck-build-logic/src/main/resources/allowed-docker-images/Dockerfile-nats

@@ -1 +1 @@
-FROM nats:2.10.17
+FROM nats:2.10.21