add library "Regression" (#2340)

Author: nkaaf

repositories.txt

@@ -2982,6 +2982,7 @@ https://github.com/NitrofMtl/weeklyAlarm
 https://github.com/njh/EtherCard
 https://github.com/njh/EtherSia
 https://github.com/nkaaf/Arduino-List
+https://github.com/nkaaf/Arduino-Regression
 https://github.com/nkaaf/Arduino-Signature
 https://github.com/Nkawu/TFT_22_ILI9225
 https://github.com/nkolban/ESP32_BLE_Arduino