**Apache Airflow version**: 2.0.1


**Kubernetes version (if you are using kubernetes)** (use `kubectl version`): 1.20.5

**Environment**:

- **Cloud provider or hardware configuration**: Azure AKS

**What happened**:

When task or dag name is defined with a non ascii character, pod creations fails with a kubernetes.client.rest.ApiException: (422)
(task maintains scheduled status)
this is because the hostname defined for the pod is based on dag and task name...

**What you expected to happen**:

Create the pod and run the task

**How to reproduce it**:
Run a task with name "campaña" on K8s executor,

Error log
```
{"kind":"Status","apiVersion":"v1","metadata":{},"status":"Failure","message":"Pod \"dagnamecampaña.0fb696e661e347968216df454b41b56f\" is invalid: metadata.name: Invalid value: \"dagnamecampaña.0fb696e661e347968216df454b41b56f\": a lowercase RFC 1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0
-9])?(\\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*')","reason":"Invalid"
```



tests/executors/test_kubernetes_executor.py
self.kubernetes_executor = KubernetesExecutor()
        self.kubernetes_executor.job_id = "5"
    @unittest.skipIf(AirflowKubernetesScheduler is None, 'kubernetes python package is not installed')
    @mock.patch('airflow.executors.kubernetes_executor.KubernetesJobWatcher')
    @mock.patch('airflow.executors.kubernetes_executor.get_kube_client')
    def test_run_next_exception(self, mock_get_kube_client, mock_kubernetes_job_watcher):
        import sys
        path = sys.path[0] + '/tests/kubernetes/pod_generator_base_with_secrets.yaml'
        
        response = HTTPResponse(
            body='{"kind": "Status", "apiVersion": "v1", "metadata": {}, "status": "Failure", '
            '"message": "pods \\"podname\\" is forbidden: exceeded quota: compute-resources, '
            'requested: limits.memory=4Gi, used: limits.memory=6508Mi, limited: limits.memory=10Gi", '
            '"reason": "Forbidden", "details": {"name": "podname", "kind": "pods"}, "code": 403}'
        )
        response.status = 403
        response.reason = "Forbidden"
        
        mock_kube_client = mock.patch('kubernetes.client.CoreV1Api', autospec=True)
        mock_kube_client.create_namespaced_pod = mock.MagicMock(side_effect=ApiException(http_resp=response))
        mock_get_kube_client.return_value = mock_kube_client
        mock_api_client = mock.MagicMock()