Add ESP32Feature28 library (#7469)

* Update repositories.txt

* Add ESP32Feature28 library

Adding ESP32Feature28 library for extracting 28 audio features from I2S microphones on ESP32.

Library provides Peak Frequency, Spectral Centroid, and MFCC coefficients for ML/AI applications.

Author: HuuPhuoc2411

repositories.txt

@@ -8770,4 +8770,4 @@ https://github.com/Bodobolero/PostgrestClient
 https://github.com/ronibandini/DFR1173-Voice-Prompter
 https://github.com/marinpopa/AsyncWiFiManagerSimple
 https://github.com/NitrofMtl/STM32RS485DMA
-
+https://github.com/HuuPhuoc2411/ESP32Feature28