Add HS3UKA_PCF8574 library

[HS3UKA]

No description provided.

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/HS3UKA/HS3UKA_PCF8574:

Linting library in HS3UKA_PCF8574
WARNING: Invalid category field value Input/Output in library.properties                                       
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format
         (Rule LP038)                                                                                          

Linter results for project: 0 ERRORS, 1 WARNINGS

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

Linting sketch in HS3UKA_PCF8574/examples/digitalRead

Linter results for project: no errors or warnings

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

Linting sketch in HS3UKA_PCF8574/examples/digitalWrite

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/HS3UKA/HS3UKA_PCF8574/