Remove a duplicated line? (#6010)

Update __init__.py

Author: sweetcocoa

src/diffusers/pipelines/stable_diffusion/__init__.py

@@ -34,7 +34,6 @@
     _import_structure["pipeline_stable_diffusion"] = ["StableDiffusionPipeline"]
     _import_structure["pipeline_stable_diffusion_attend_and_excite"] = ["StableDiffusionAttendAndExcitePipeline"]
     _import_structure["pipeline_stable_diffusion_gligen"] = ["StableDiffusionGLIGENPipeline"]
-    _import_structure["pipeline_stable_diffusion_gligen"] = ["StableDiffusionGLIGENPipeline"]
     _import_structure["pipeline_stable_diffusion_gligen_text_image"] = ["StableDiffusionGLIGENTextImagePipeline"]
     _import_structure["pipeline_stable_diffusion_img2img"] = ["StableDiffusionImg2ImgPipeline"]
     _import_structure["pipeline_stable_diffusion_inpaint"] = ["StableDiffusionInpaintPipeline"]