add M5Unit-IMU-Pro-Mini lib

[Gitshaoxiang]

add M5Unit-IMU-Pro-Mini lib

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/m5stack/M5Unit-IMU-Pro-Mini:

Linting library in M5Unit-IMU-Pro-Mini
INFO: No header file found matching library name (M5Unit-IMU-Pro-Mini.h). Best practices are for primary header filename
      to match library name.                                                                                            
      See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format            
      (Rule LS008)                                                                                                      
WARNING: library.properties name value M5Unit-IMU-Pro-Mini 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: library.properties depends field item(s) M5Adafruit BMP280 Library not found in the Library Manager index.
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format    
         (Rule LP048)                                                                                              

Linter results for project: 0 ERRORS, 2 WARNINGS

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

Linting sketch in M5Unit-IMU-Pro-Mini/examples/AHRS

Linter results for project: no errors or warnings

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

Linting sketch in M5Unit-IMU-Pro-Mini/examples/getSensorData

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/m5stack/M5Unit-IMU-Pro-Mini/