Update repositories.txt (#4427)

Author: sdmueller

repositories.txt

@@ -5431,11 +5431,13 @@ https://github.com/Sensirion/arduino-i2c-sht4x
 https://github.com/Sensirion/arduino-i2c-stc3x
 https://github.com/Sensirion/arduino-i2c-sts4x
 https://github.com/sensirion/arduino-i2c-svm4x
+https://github.com/Sensirion/arduino-i2c-sfx6xxx
 https://github.com/Sensirion/arduino-sht
 https://github.com/Sensirion/arduino-sps
 https://github.com/Sensirion/arduino-uart-sen44
 https://github.com/Sensirion/arduino-uart-sfa3x
 https://github.com/sensirion/arduino-uart-svm4x
+https://github.com/Sensirion/arduino-uart-sfx6xxx
 https://github.com/Sensirion/arduino-upt-core
 https://github.com/Sensirion/arduino-upt-i2c-auto-detection
 https://github.com/Sensirion/arduino-upt-ble-auto-detection