Update repositories.txt

Added Renke_DissolvedOxygen_Sensor to the repositories.txt file.

Author: bartzdev

repositories.txt

@@ -7891,3 +7891,4 @@ https://github.com/mlesniew/PicoSyslog
 https://github.com/Jonathan-Z-Code/DHT11_Sensor
 https://github.com/MIPSLabs/MipsLib
 https://github.com/bastian2001/pico-bidir-dshot
+https://github.com/bartzdev/Renke_DissolvedOxygen_Sensor