Update repositories.txt

[NitrofMtl]

add DUE_Oversampler

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/NitrofMtl/DUE_ADC_Oversampler:

Linting library in DUE_ADC_Oversampler
WARNING: library.properties name value DUE_ADC_Oversampler is longer than the recommended length of 16 characters.
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format   
         (Rule LP010)                                                                                             
WARNING: Unable to load the library.properties url field: Head "https://https//github.com/NitrofMtl/ADC_Sampler": dial  
         tcp: lookup https: Temporary failure in name resolution                                                        
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format         
         (Rule LP042)                                                                                                   

Linter results for project: 0 ERRORS, 2 WARNINGS

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

Linting sketch in DUE_ADC_Oversampler/examples/ADC_Oversampler_example

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/NitrofMtl/DUE_ADC_Oversampler/