Fix unhandled exception when Swisscom Internet Box is not responsive (#28618)

* Update device_tracker.py

From time to time, Swisscom Internet Box fails to respond and this causes an exception, which is currently not handled by the code:

Traceback (most recent call last):
  File "/srv/homeassistant/lib/python3.7/site-packages/homeassistant/components/device_tracker/setup.py", line 164, in async_device_tracker_scan
    found_devices = await scanner.async_scan_devices()
  File "/usr/local/lib/python3.7/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/srv/homeassistant/lib/python3.7/site-packages/homeassistant/components/swisscom/device_tracker.py", line 46, in scan_devices
    self._update_info()
  File "/srv/homeassistant/lib/python3.7/site-packages/homeassistant/components/swisscom/device_tracker.py", line 67, in _update_info
    data = self.get_swisscom_data()
  File "/srv/homeassistant/lib/python3.7/site-packages/homeassistant/components/swisscom/device_tracker.py", line 83, in get_swisscom_data
    request = requests.post(url, headers=headers, data=data, timeout=10)
  File "/srv/homeassistant/lib/python3.7/site-packages/requests/api.py", line 116, in post
    return request('post', url, data=data, json=json, **kwargs)
  File "/srv/homeassistant/lib/python3.7/site-packages/requests/api.py", line 60, in request
    return session.request(method=method, url=url, **kwargs)
  File "/srv/homeassistant/lib/python3.7/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/srv/homeassistant/lib/python3.7/site-packages/requests/sessions.py", line 686, in send
    r.content
  File "/srv/homeassistant/lib/python3.7/site-packages/requests/models.py", line 828, in content
    self._content = b''.join(self.iter_content(CONTENT_CHUNK_SIZE)) or b''
  File "/srv/homeassistant/lib/python3.7/site-packages/requests/models.py", line 757, in generate
    raise ConnectionError(e)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='192.168.1.1', port=80): Read timed out.

I've just added a try-except around the post.

* Update device_tracker.py

Addressed blank line issue reported by flake8

* Update device_tracker.py

Fixed alignment to be Black compliant.

* Update device_tracker.py

Fixed one more alignment issue

homeassistant/components/swisscom/device_tracker.py

@@ -80,9 +80,18 @@ class SwisscomDeviceScanner(DeviceScanner):
         {"service":"Devices", "method":"get",
         "parameters":{"expression":"lan and not self"}}"""
 
-        request = requests.post(url, headers=headers, data=data, timeout=10)
-
         devices = {}
+
+        try:
+            request = requests.post(url, headers=headers, data=data, timeout=10)
+        except (
+            requests.exceptions.ConnectionError,
+            requests.exceptions.Timeout,
+            requests.exceptions.ConnectTimeout,
+        ):
+            _LOGGER.info("No response from Swisscom Internet Box")
+            return devices
+
         for device in request.json()["status"]:
             try:
                 devices[device["Key"]] = {