xgraph Subgraphx files has typo resulting in erroneous test accuracy

[ahoefn]

Description

In following file in the xgraph/Subgraphx directory of the main branch, there seems to be a typo on line 82. Here, the test accuracy is calculated using the code
test_state, _, _ = test_GC(dataloader['train'], gnnNets, criterion)
The test_GC function then calculates accuracy and the loss. However, the 'test' subset of the data should be used here instead (see e.g. line 170 of the same file).

Suggested fix

Change 'train' to 'test'.