fix(build): re-add sentencepiece which is apparently needed by gguf, but is not defined as its dependency

Author: ebr

pyproject.toml

@@ -45,6 +45,7 @@ dependencies = [
   "onnxruntime==1.19.2",
   "opencv-python==4.9.0.80",
   "safetensors",
+  "sentencepiece",
   "spandrel",
   "torch~=2.6.0",                         # torch and related dependencies are loosely pinned, will respect requirement of `diffusers[torch]`
   "torchsde",                             # diffusers needs this for SDE solvers, but it is not an explicit dep of diffusers