hotfix: 0.12.1 void order status check

[eoin-betdex]

When orders are cancelled in certain cases and are kept open with their status updated to Cancelled the market settled_account_count is decremented. If that market is subsequently voided, then void_order incorrectly also decrements settled_account_count for those orders. This can result in the settled_account_count prematurely reaching 0 and preventing market voiding from completing completely.

This fix corrects void_order, preventing Cancelled orders from affecting the market's settled_account_count during voiding.

This issue was introduced in 0.12.0. Correct handling of Cancelled orders was added to order settlement, but was missed from order voiding.