Update to use number_of_stored_values instead of nnz

Author: BenBrock

include/binsparse/read_matrix.h

@@ -35,7 +35,8 @@ bsp_matrix_t bsp_read_matrix_from_group(hid_t f) {
 
   matrix.format = format;
 
-  cJSON* nnz_ = cJSON_GetObjectItemCaseSensitive(binsparse, "nnz");
+  cJSON* nnz_ =
+      cJSON_GetObjectItemCaseSensitive(binsparse, "number_of_stored_values");
   assert(nnz_ != NULL);
   size_t nnz = cJSON_GetNumberValue(nnz_);
 

include/binsparse/write_matrix.h

@@ -33,7 +33,7 @@ char* bsp_generate_json(bsp_matrix_t matrix, cJSON* user_json) {
   cJSON_AddItemToArray(shape, nrows);
   cJSON_AddItemToArray(shape, ncols);
 
-  cJSON_AddNumberToObject(binsparse, "nnz", matrix.nnz);
+  cJSON_AddNumberToObject(binsparse, "number_of_stored_values", matrix.nnz);
 
   cJSON* data_types = cJSON_AddObjectToObject(binsparse, "data_types");