Fix samsungtv to abort when ATTR_UPNP_MANUFACTURER is missing

[bdraco]

Proposed change

Fixes

2022-09-20 08:47:23.807 ERROR (MainThread) [homeassistant] Error doing job: Task exception was never retrieved
Traceback (most recent call last):
  File "/Users/bdraco/home-assistant/homeassistant/data_entry_flow.py", line 225, in async_init
    flow, result = await task
  File "/Users/bdraco/home-assistant/homeassistant/data_entry_flow.py", line 252, in _async_init
    result = await self._async_handle_step(flow, flow.init_step, data, init_done)
  File "/Users/bdraco/home-assistant/homeassistant/data_entry_flow.py", line 367, in _async_handle_step
    result: FlowResult = await getattr(flow, method)(user_input)
  File "/Users/bdraco/home-assistant/homeassistant/components/samsungtv/config_flow.py", line 461, in async_step_ssdp
    self._manufacturer = discovery_info.upnp[ssdp.ATTR_UPNP_MANUFACTURER]
KeyError: manufacturer

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
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[probot-home-assistant]

Hey there @chemelli74, @epenet, mind taking a look at this pull request as it has been labeled with an integration (samsungtv) you are listed as a code owner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[epenet]

LGTM