**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, mock_adopt_completed_pods, mock_adopt_launched_task
    ):
        executor = self.kubernetes_executor
        mock_ti = mock.MagicMock(queued_by_job_id="1", external_executor_id="1", dag_id="dag", task_id="task")
        mock_kube_client = mock.MagicMock()
        mock_kube_client.list_namespaced_pod.return_value.items = []
        executor.kube_client = mock_kube_client
        tis_to_flush = executor.try_adopt_task_instances([mock_ti])
        assert tis_to_flush == [mock_ti]
        mock_adopt_launched_task.assert_not_called()
        mock_adopt_completed_pods.assert_called_once()
    @mock.patch('airflow.executors.kubernetes_executor.get_kube_client')
    def test_adopt_launched_task(self, mock_kube_client):