ModernBERT model (#2713)

* layer_norm_no_bias

* Modernbert model.

* Format + cleanup error.

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Co-authored-by: laurent <laurent.mazare@gmail.com>

candle-transformers/src/models/mod.rs

@@ -60,6 +60,7 @@ pub mod mmdit;
 pub mod mobileclip;
 pub mod mobilenetv4;
 pub mod mobileone;
+pub mod modernbert;
 pub mod moondream;
 pub mod mpt;
 pub mod nvembed_v2;