add TinyScheduler library (#5124)

Author: ettoreleandrotognoli

repositories.txt

@@ -4498,6 +4498,7 @@ https://github.com/OpenBCI/OpenBCI_Radios
 https://github.com/OpenBCI/OpenBCI_WIFI
 https://github.com/OpenBCI/OpenBCI_Wifi_Master_Library
 https://github.com/OpenCIAg/BlueFairy
+https://gitlab.com/ettotog/tiny-scheduler
 https://github.com/OpenDevice/opendevice-lib-arduino
 https://github.com/openenergymonitor/EmonLib
 https://github.com/OpenFTC/HiTechnic-Arduino