feat: Convert to installable package

[mathiasesn]

This pull request includes several changes to the pose-estimation project, focusing on the removal of the yolov5 submodule, refactoring of the pose/infer.py file, and the addition of a pyproject.toml file for project configuration and dependencies.

Removal of yolov5 submodule:

• .gitmodules: Removed the yolov5 submodule configuration.
• yolov5: Removed the yolov5 submodule commit.

Refactoring and improvements in pose/infer.py:

• pose/infer.py: Renamed from infer.py, reorganized imports, and replaced yolov5 model loading with ultralytics.YOLO.
• pose/infer.py: Updated Pose class initialization to use YOLO for det_model and refactored code for better readability and consistency. [1] [2] [3] [4] [5]

Addition of pyproject.toml:

• pyproject.toml: Added a new file to specify project metadata, dependencies, and build system configuration using hatchling.