fix typo in ogbl_collab.py.

Author: baoleai

examples/data/ogbl_collab.py

@@ -32,7 +32,7 @@
 node_feat = graph['node_feat'] # shape(235868, 128)
 
 # dump to disk
-root = 'ogbl_collab'
+root = 'ogbl_collab/'
 train_table = root + 'ogbl_collab_train_edge'
 val_table = root + 'ogbl_collab_val_edge'
 test_table = root + 'ogbl_collab_test_edge'
@@ -73,4 +73,4 @@
   f.write('src_id:int64' + '\t' + 'dst_id:int64' + '\t' + 'weight:double\n')
   for i in range(len(test_edge['edge_neg'])):
     f.write(str(test_edge['edge_neg'][i, 0]) + '\t' + str(test_edge['edge_neg'][i, 1])
-        + '\t' + '1.0\n')
+        + '\t' + '1.0\n')