corrects single file path validation logic

[andrew-w-ross]

What does this PR do?

Fix's loading ModularPipelines loading component specs where pretrained_model_name_or_path is a path.

Didn't bother opening an issue considering the tiny size of the fix.

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[DN6]

Thank you @andrew-w-ross! Small change requested to the test, but good to merge once that's updated 👍🏽

[DN6]

Small update to the test so we use a tiny controlnet instead of the larger ~1GB one in this test.

Suggested change

	def test_load_components_loads_local_single_file_path(self, tmp_path):
	pipe = ModularPipeline.from_pretrained("hf-internal-testing/tiny-stable-diffusion-xl-pipe")
	local_ckpt_path = hf_hub_download(
	repo_id="lllyasviel/ControlNet-v1-1",
	filename="control_v11p_sd15_canny.pth",
	local_dir=str(tmp_path),
	)
	pipe._component_specs["controlnet"] = ComponentSpec(
	name="controlnet",
	type_hint=ControlNetModel,
	pretrained_model_name_or_path=local_ckpt_path,
	)
	pipe.load_components(names="controlnet")
	assert pipe.controlnet is not None
	assert isinstance(pipe.controlnet, ControlNetModel)
	assert pipe._component_specs["controlnet"].pretrained_model_name_or_path == local_ckpt_path
	assert getattr(pipe.controlnet, "_diffusers_load_id", None) not in (None, "null")
	def test_load_components_loads_local_single_file_path(self, tmp_path):
	pipe = ModularPipeline.from_pretrained("hf-internal-testing/tiny-stable-diffusion-xl-pipe")
	model = ControlNetModel.from_pretrained("hf-internal-testing/tiny-controlnet")
	model.save_pretrained(tmp_path)
	local_ckpt_path = str(tmp_path / "diffusion_pytorch_model.safetensors")
	pipe._component_specs["controlnet"] = ComponentSpec(
	name="controlnet",
	type_hint=ControlNetModel,
	pretrained_model_name_or_path=local_ckpt_path,
	)
	pipe.load_components(names="controlnet", config=str(tmp_path))
	assert pipe.controlnet is not None
	assert isinstance(pipe.controlnet, ControlNetModel)
	assert pipe._component_specs["controlnet"].pretrained_model_name_or_path == local_ckpt_path
	assert getattr(pipe.controlnet, "_diffusers_load_id", None) not in (None, "null")