F401 fixes for ruff

extensions-builtin/LDSR/scripts/ldsr_model.py

modules/cmd_args.py

modules/deepbooru.py

modules/extensions.py

modules/gfpgan_model.py

modules/models/diffusion/uni_pc/__init__.py

modules/paths.py

modules/realesrgan_model.py

modules/script_loading.py

modules/sd_hijack_inpainting.py

modules/sd_models.py

modules/sd_samplers.py

modules/shared.py

modules/ui.py

modules/upscaler.py

pyproject.toml

webui.py