[card_weather] - use entity temperature when ulm_card_weather_custom isn't set

[shogun160]

use entity temperature when ulm_card_weather_custom isn't set

Additional information

• This PR fixes or closes issue: fixes Since the update to 1.2.0 Weather Card does not display #1192
• This PR is related to issue: Weather #1201 (PR to revert PR Add custom weather data support to Weather Card #1170)
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• I have followed the contribution guidelines
  • This PR is for a custom-card or documentation change and therefore directed to the main branch.
  • This PR is for a official card or any other directly to the integration related change and therefore directed to the release branch.

[shogun160]

no need to update readme