add library aht20 (#2347)

* Update repositories.txt

* Update repositories.txt

Co-authored-by: per1234 <[email protected]>

Author: dvarrel

repositories.txt

@@ -5503,6 +5503,7 @@ https://github.com/WindyWanderer/CSWBattery.git
 https://github.com/stm32duino/STM32LoRaWAN
 https://github.com/SyntaxHarvy/HaCEspSockets
 https://github.com/kermite-org/keyboard_peripheral_modules
+https://github.com/dvarrel/AHT20
 https://github.com/kermite-org/KermiteCore_Arduino
 https://github.com/dvarrel/BMP280
 https://github.com/chandrawi/U8x_Laser_Distance