Update repositories.txt

[cparata]

Please add "STM32duino X-NUCLEO-IHM15A1" library to Library Manager.
Best Regards,
Carlo

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/stm32duino/X-NUCLEO-IHM15A1:

Linting library in X-NUCLEO-IHM15A1
INFO: No header file found matching library name (STM32duino_X-NUCLEO-IHM15A1.h). Best practices are for primary header 
      filename to match library name. (Rule LS008)                                                                      
WARNING: library.properties name value STM32duino X-NUCLEO-IHM15A1 is longer than the recommended length of 16          
         characters. (Rule LP010)                                                                                       
WARNING: library.properties name STM32duino X-NUCLEO-IHM15A1 contains spaces. Although supported, best practices is to  
         not use spaces. (Rule LP015)                                                                                   

Linter results for project: 0 ERRORS, 2 WARNINGS

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

Linting sketch in X-NUCLEO-IHM15A1/examples/X_NUCLEO_IHM15A1_HelloWorld

Linter results for project: no errors or warnings

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

Linter results for projects: 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/stm32duino/X-NUCLEO-IHM15A1/