Update repositories.txt (#5478)

Arduino library for analog TEMT6000 light / LUX sensor.

Author: RobTillaart

repositories.txt

@@ -5482,6 +5482,7 @@ https://github.com/RobTillaart/SWSPI
 https://github.com/RobTillaart/TCA9548
 https://github.com/RobTillaart/TCA9555
 https://github.com/RobTillaart/Temperature
+https://github.com/RobTillaart/TEMT6000
 https://github.com/RobTillaart/timing
 https://github.com/RobTillaart/TinyKT0803
 https://github.com/RobTillaart/tinySHT2x