Adding MLX90641 library to repositories.txt

[dndubins]

This is a small library to read the MLX90641 16x12 IR camera using the ESP32.

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/dndubins/MLX90641:

Linting library in MLX90641
WARNING: Invalid category field value Sensor in library.properties                                             
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format
         (Rule LP038)                                                                                          
WARNING: No example sketches found. Please provide examples.                                      
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#library-examples
         (Rule LD004)                                                                             

Linter results for project: 0 ERRORS, 2 WARNINGS

-------------------

[github-actions]

Your submission has now been accepted! Thanks for your contribution to the Arduino Library Manager index.

The library(s) will be available for installation via Library Manager within a day's time.

You can check the logs from the Library Manager indexer for your library(s) here:
http://downloads.arduino.cc/libraries/logs/github.com/dndubins/MLX90641/