Update repositories.txt (#5895)

Arduino library for (AVR) faster and extended output pin.

Author: RobTillaart

repositories.txt

@@ -5537,6 +5537,7 @@ https://github.com/RobTillaart/Multiplex
 https://github.com/RobTillaart/NeumannCorrector
 https://github.com/RobTillaart/nibbleArray
 https://github.com/RobTillaart/Optoma
+https://github.com/RobTillaart/OUTPIN
 https://github.com/RobTillaart/palindrome
 https://github.com/RobTillaart/PAR27979
 https://github.com/RobTillaart/ParallelPrinter