Update onnx_config.pbtxt

onnx_config.pbtxt

@@ -5,19 +5,19 @@ input [
   {
     name: "input_ids"
     data_type: TYPE_INT64
-    dims: [ 512 ]
+    dims: [ -1, 512 ]
   },
   {
     name: "attention_mask"
     data_type: TYPE_INT64
-    dims: [ 512 ]
+    dims: [ -1, 512 ]
   }
 ]
 output [
   {
     name: "logits"
     data_type: TYPE_FP32
-    dims: [ 2 ]
+    dims: [ -1, 2 ]
   }
 ]
 instance_group [