Add Sensirion I2C SHT4x to library index

[rnestler]

No description provided.

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/Sensirion/arduino-i2c-sht4x:

Linting library in arduino-i2c-sht4x
INFO: No header file found matching library name (Sensirion_I2C_SHT4x.h). Best practices are for primary header filename
      to match library name. (Rule LS008)                                                                               
WARNING: library.properties name value Sensirion I2C SHT4x is longer than the recommended length of 16 characters. (Rule
         LP010)                                                                                                         
WARNING: library.properties name Sensirion I2C SHT4x contains spaces. Although supported, best practices is to not use  
         spaces. (Rule LP015)                                                                                           
WARNING: Missing architectures field in library.properties. See                                                         
         https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format (Rule LP043) 

Linter results for project: 0 ERRORS, 3 WARNINGS

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Linting sketch in arduino-i2c-sht4x/examples/exampleUsage

Linter results for project: no errors or warnings

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

Linter results for projects: 0 ERRORS, 3 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/Sensirion/arduino-i2c-sht4x/