Update repositories.txt (#3955)

Arduino Library for DS2438 1-Wire battery monitor

Author: RobTillaart

repositories.txt

@@ -1802,6 +1802,7 @@ https://github.com/RobTillaart/DS1821
 https://github.com/RobTillaart/DS18B20
 https://github.com/RobTillaart/DS18B20_INT
 https://github.com/RobTillaart/DS2401
+https://github.com/RobTillaart/DS2438
 https://github.com/RobTillaart/DS28CM00
 https://github.com/RobTillaart/DistanceTable
 https://github.com/RobTillaart/FLE