Push to self-signed certificate mirror failed

### Describe the issue
```yaml
- id: docker_build_schema
type: io.kestra.plugin.docker.Build
tags:
- "{{ outputs.schema_test_tag_output.value }}"
dockerfile: "space/deploy/schema/Dockerfile"
push: true
config: |
{
"auths": {
"192.168.122.98:5000": {
"auth": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
}
}
}
platforms:
- linux/amd64
buildArgs:
TARGETARCH: amd64
TARGETOS: linux
credentials:
registry: "{{ inputs.docker_repository }}"
username: "{{ secret('DOCKER_HUB_USERNAME') }}"
password: "{{ secret('DOCKER_HUB_PAT') }}"
```
```bash

2025-07-25 15:39:57.759docker_build_schema
Get "https://192.168.122.98:5000/v2/": tls: failed to verify certificate: x509: certificate signed by unknown authority
```
How to bypass
### Environment

- Kestra Version: develop

Start from the Docker Build task and its registry push handling, using the issue's self-signed registry configuration to reproduce the TLS verification failure. Determine the supported way to trust or bypass the certificate, then verify that the image can be pushed to the shown registry without the x509 error.

Written by the indexing model from the issue text.