add send and sync trait bounds for scheduler config in stable diffusion models (#1952)

* first commit

* add Sync deriving

* static

* remove static

candle-transformers/src/models/stable_diffusion/schedulers.rs

@@ -5,7 +5,7 @@
 //! inference speed and quality.
 use candle::{Result, Tensor};
 
-pub trait SchedulerConfig: std::fmt::Debug {
+pub trait SchedulerConfig: std::fmt::Debug + Send + Sync {
     fn build(&self, inference_steps: usize) -> Result<Box<dyn Scheduler>>;
 }