**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.events.append({"type": 'MODIFIED', "object": self.pod})
        self._run()
        self.watcher.watcher_queue.put.assert_not_called()
    def test_process_status_pending_deleted(self):
        self.events.append({"type": 'DELETED', "object": self.pod})
        self._run()
        self.assert_watcher_queue_called_once_with_state(State.FAILED)
    def test_process_status_failed(self):
        self.pod.status.phase = "Failed"
        self.events.append({"type": 'MODIFIED', "object": self.pod})
        self._run()
        self.assert_watcher_queue_called_once_with_state(State.FAILED)
    def test_process_status_succeeded(self):
        self.pod.status.phase = "Succeeded"
        self.events.append({"type": 'MODIFIED', "object": self.pod})
        self._run()
        self.assert_watcher_queue_called_once_with_state(None)
    def test_process_status_running(self):
        self.pod.status.phase = "Running"
        self.events.append({"type": 'MODIFIED', "object": self.pod})
        self._run()
        self.watcher.watcher_queue.put.assert_not_called()
    def test_process_status_catchall(self):