Update repositories.txt

[ladyada]

https://github.com/adafruit/Adafruit_OPT4048

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/adafruit/Adafruit_OPT4048:

Linting library in Adafruit_OPT4048
WARNING: library.properties name Adafruit OPT4048 contains spaces. Although supported, best practices is to not use     
         spaces.                                                                                                        
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format         
         (Rule LP015)                                                                                                   
WARNING: No license file found.                                                                                                                 
         See:                                                                                                                                   
         https://docs.github.com/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/licensing-a-repository
         (Rule LD002)                                                                                                                           

Linter results for project: 0 ERRORS, 2 WARNINGS

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

Linting sketch in Adafruit_OPT4048/examples/opt4048_basictest

Linter results for project: no errors or warnings

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

Linting sketch in Adafruit_OPT4048/examples/opt4048_fulltest

Linter results for project: no errors or warnings

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

Linting sketch in Adafruit_OPT4048/examples/opt4048_intpin

Linter results for project: no errors or warnings

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

Linting sketch in Adafruit_OPT4048/examples/opt4048_oneshot

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/adafruit/Adafruit_OPT4048/