build(deps): bump github.com/nats-io/nats-server/v2

Bumps [github.com/nats-io/nats-server/v2](https://github.com/nats-io/nats-server) from 2.11.9 to 2.12.0.
- [Release notes](https://github.com/nats-io/nats-server/releases)
- [Changelog](https://github.com/nats-io/nats-server/blob/main/.goreleaser.yml)
- [Commits](https://github.com/nats-io/nats-server/compare/v2.11.9...v2.12.0)

---
updated-dependencies:
- dependency-name: github.com/nats-io/nats-server/v2
  dependency-version: 2.12.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

vendor/github.com/nats-io/jwt/v2/user_claims.go

@@ -36,6 +36,7 @@ type UserPermissionLimits struct {
 	Permissions
 	Limits
 	BearerToken            bool       `json:"bearer_token,omitempty"`
+	ProxyRequired          bool       `json:"proxy_required,omitempty"`
 	AllowedConnectionTypes StringList `json:"allowed_connection_types,omitempty"`
 }