Update repositories.txt

[Naguissa]

Add uMessagesBrokerLib

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/Naguissa/uMessagesBrokerLib:

Linting library in uMessagesBrokerLib
WARNING: library.properties name value uMessagesBrokerLib is longer than the recommended length of 16 characters.
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format  
         (Rule LP010)                                                                                            

Linter results for project: 0 ERRORS, 1 WARNINGS

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Linting sketch in uMessagesBrokerLib/examples/uHexLib_example

Linter results for project: no errors or warnings

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Linting sketch in uMessagesBrokerLib/examples/uHexLib_example_arrays

Linter results for project: no errors or warnings

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Linting sketch in uMessagesBrokerLib/examples/uMessagesBrokerLib_example

Linter results for project: no errors or warnings

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Linter results for projects: 0 ERRORS, 1 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/Naguissa/uMessagesBrokerLib/