Incorrect variable used

[david-holbrook]

Describe the bug
I think for the following two variables:

--st-mode-active-color
--st-toggle-label-color

They are refencing the host variable var(--text-primary-color)

This should actually be var(--primary-text-color)

To Reproduce
Screenshots below

Expected behavior
The active mode button text should be black (or white in dark mode).

# The least ammount of code possible to reproduce my error

type: 'custom:simple-thermostat'
entity: climate.xxx

**Screenshots**
Original
![image](https://user-images.githubusercontent.com/86042175/231740787-ede0070d-1ad2-4f76-a0b2-f84ac44f55b8.png)

Corrected with card-mod
![image](https://user-images.githubusercontent.com/86042175/231740973-31bfed18-4be8-4722-8b4f-6b5a90887186.png)

**Browser**
 - OS: Mac/Win/iOS/Android
 - Browser: Chrome/Firefox/Mobile app?
 - Simple Thermostat version from browser console: 
 - Home Assistant version: