fix: fix num_ln_in_parallel_attn attribute name typo in RWConfig (#2350)

Co-authored-by: Islam Almersawi <islam.almersawi@openinnovation.ai>

server/text_generation_server/models/custom_modeling/flash_rw_modeling.py

@@ -94,7 +94,7 @@ class RWConfig(PretrainedConfig):
             else kwargs.pop("n_head", 8)
         )
         self.layer_norm_epsilon = layer_norm_epsilon
-        self.num_ln_in_parallel_attention = num_ln_in_prallel_attention
+        self.num_ln_in_parallel_attn = num_ln_in_prallel_attention
         self.initializer_range = initializer_range
         self.use_cache = use_cache
         self.hidden_dropout = hidden_dropout