Update repositories.txt (#3721)

Added SparkFun Toolkit

Author: gigapod

repositories.txt

@@ -5553,6 +5553,7 @@ https://github.com/sparkfun/SparkFun_u-blox_GNSS_Arduino_Library
 https://github.com/sparkfun/SparkFun_u-blox_GNSS_v3
 https://github.com/sparkfun/SparkFun_u-blox_SARA-R5_Arduino_Library
 https://github.com/sparkfun/Sparkfun_RGB_OLED_64x64_Arduino_Library
+https://github.com/sparkfun/SparkFun_Toolkit
 https://github.com/sparkfun/phant-arduino
 https://github.com/sphero-inc/sphero-sdk-arduino-cpp-library-manager
 https://github.com/spicajames/Rtttl