Updated repositories.txt

[rtnate]

Add https://github.com/rtnate/Arduino-DS1881_2 to list

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/rtnate/Arduino-DS1881_2:

Linting library in Arduino-DS1881_2
WARNING: Git submodule detected. Library Manager installations and installations from GitHub's "Download ZIP" will only 
         contain an empty folder in place of the submodule. (Rule LS004)                                                
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

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[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/rtnate/Arduino-DS1881_2/