Description

• Corrected the PYTHONPATH environment variable to ensure it contains the correct stable-diffusion-webui root directory path during the extension installation process.
• Added a nested try/except block within the run_extension_installer function. The try block attempts to add the correct stable-diffusion-webui root path to the PYTHONPATH environment variable. It does this by converting the relative path (from modules/launch_utils.py to the project root) to an absolute path. The Path from the pathlib library is imported for this purpose.
• Code style has been checked with python -m ruff check
• I solved the problem that described in [Feature Request]: Extentions can't use A1111 modules in correct way #15697

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests