Update repositories.txt

[RoboCore]

Add the "RoboCore - Vespa" library.

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/RoboCore/RoboCore_Vespa:

Linting library in RoboCore_Vespa
INFO: No header file found matching library name (RoboCore_-_Vespa.h). Best practices are for primary header filename to
      match library name. (Rule LS008)                                                                                  
WARNING: library.properties name RoboCore - Vespa contains spaces. Although supported, best practices is to not use     
         spaces. (Rule LP015)                                                                                           

Linter results for project: 0 ERRORS, 1 WARNINGS

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Linting sketch in RoboCore_Vespa/examples/Blink

Linter results for project: no errors or warnings

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Linting sketch in RoboCore_Vespa/examples/Button

Linter results for project: no errors or warnings

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Linting sketch in RoboCore_Vespa/examples/Motors

Linter results for project: no errors or warnings

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Linting sketch in RoboCore_Vespa/examples/SupplyVoltage

Linter results for project: no errors or warnings

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Linting sketch in RoboCore_Vespa/examples/Sweep

Linter results for project: no errors or warnings

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

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/RoboCore/RoboCore_Vespa/