fix handling of signed values

[jensgraef]

This pull request fixes an issue introduced in #43. Thanks for finding it, @qschneider

[qschneider]

Hi, i tested your fix, but it doesn't change the output. I noticed that the "negative" number is much greater than it was before you introduced signed value handling in the frist place. I used the settings below.

external_components:

• source: github://the78mole/esphome_components/tree/fix-signed-value-handling components: [ km271_wifi ] refresh: 1sec

and got this output

logs_esp32-km271-hz_logs.txt

[jensgraef]

@qschneider: Would you mind trying to add ref:fix-signed-value-handling to the definition of the external component? According to https://esphome.io/components/external_components.html that's the way how to select a certain branch.

[qschneider]

once you do it the right way... :-)

• source: github://the78mole/esphome_components@fix-signed-value-handling worked for me.

signed values bug is fixed, thanks!