fix paddle 2.6.0 problem with zipping iterables of tensors

ivy/functional/backends/paddle/general.py

@@ -227,6 +227,10 @@ def _gather(params1):
     return _gather(params)
 
 
+@with_unsupported_device_and_dtypes(
+    {"2.5.2 and below": {"cpu": ("bfloat16", "float16")}},
+    backend_version,
+)
 def gather_nd(
     params: paddle.Tensor,
     indices: paddle.Tensor,
@@ -269,6 +273,8 @@ def gather_nd(
     indices_shape = indices.shape
     batch_shape = params_shape[:batch_dims]
     batch_size = paddle.prod(batch_shape, [0]).numpy().tolist()
+    if isinstance(batch_size, int):
+        batch_size = [batch_size]
     index_internal_ndims = indices.ndim - batch_dims - 1
     indices_internal_shape = indices_shape[batch_dims:-1]
 
@@ -647,7 +653,11 @@ def _vmap(*args, **kwargs):
 
         # vectorisation - applying map_fn if only one arg provided as reduce requires
         # two elements to begin with.
-        arr_results = [func(*arrays) for arrays in zip(*args)]
+        arr_results = []
+        for arrays in zip(*args):
+            arrays = [a if a.shape != [] else a.unsqueeze(0) for a in arrays]
+            arr_results.append(func(*arrays))
+
         res = paddle_backend.concat(arr_results)
 
         if out_axes: