Add Arduino_LowPowerPortentaC33 library (#4996)

Author: sebromero

repositories.txt

@@ -817,6 +817,7 @@ https://github.com/arduino-libraries/Arduino_HTS221
 https://github.com/arduino-libraries/Arduino_JSON
 https://github.com/arduino-libraries/Arduino_KNN
 https://github.com/arduino-libraries/Arduino_LowPowerPortentaH7
+https://github.com/arduino-libraries/Arduino_LowPowerPortentaC33
 https://github.com/arduino-libraries/Arduino_LPS22HB
 https://github.com/arduino-libraries/Arduino_LSM6DS3
 https://github.com/arduino-libraries/Arduino_LSM6DSOX