Thermostat: get the 1st decimal place

[irsl]

Context

The Broadlink Hysen thermostats do support 1 decimal precision, but this library did not extract that information. This PR provides access to the additional bit of information.

Proposed change

I decompiled a relevant Android app to learn how it extracts temperature values with 1 decimal place precision. The relevant part of the code can be found here: https://pastebin.com/EYHBJ5sn I ported the logic to this codebase and the numbers are now showing up fine in HA.

I tested this with Computherm E400RF and Computherm E280 (a product by a Hungarian vendor).

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New device
• [ ] New product id (the device is already supported with a different id)
• [x] New feature (which adds functionality to an existing device)
• [ ] Breaking change (fix/feature causing existing functionality to break)
• [ ] Code quality improvements to existing code or addition of tests
• [ ] Documentation

Checklist

• [x] The code change is tested and works locally.
• [x] The code has been formatted using Black.
• [x] The code follows the Zen of Python.
• [x] I am creating the Pull Request against the correct branch.
• [] Documentation added/updated.

[irsl]

Sorry, didn't notice the conflict. I'll file a new one soon.