Bump the regclient group across 1 directory with 2 updates

Bumps the regclient group with 2 updates in the /docker directory: sigstore/cosign/cosign and [regclient/regctl](https://github.com/regclient/regclient).


Updates `sigstore/cosign/cosign` from v3.0.5 to v3.0.6

Updates `regclient/regctl` from v0.11.2 to v0.11.3
- [Release notes](https://github.com/regclient/regclient/releases)
- [Changelog](https://github.com/regclient/regclient/blob/v0.11.3/release.md)
- [Commits](regclient/regclient@v0.11.2...v0.11.3)

---
updated-dependencies:
- dependency-name: regclient/regctl
  dependency-version: v0.11.3
  dependency-type: direct:production
  dependency-group: regclient
- dependency-name: sigstore/cosign/cosign
  dependency-version: v3.0.6
  dependency-type: direct:production
  dependency-group: regclient
...

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

Author: dependabot[bot]

docker/Dockerfile

@@ -1,8 +1,8 @@
 # syntax=docker.io/docker/dockerfile:1.20
 # From https://github.com/sigstore/cosign/releases
-FROM ghcr.io/sigstore/cosign/cosign:v3.0.5 AS cosign
+FROM ghcr.io/sigstore/cosign/cosign:v3.0.6 AS cosign
 # From https://github.com/regclient/regclient/releases
-FROM ghcr.io/regclient/regctl:v0.11.2 AS regctl
+FROM ghcr.io/regclient/regctl:v0.11.3 AS regctl
 
 FROM ghcr.io/dependabot/dependabot-updater-core