Toggling checkbox of parent does not toggle checkbox of all children (fix child node status)

[mikeogawa]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...) fixing updateChildNodeStatus

• What is the current behavior? (You can also link to an open issue here) the checkbox in the parent node does not update the child node that is located directly under the parent node.

• What is the new behavior (if this is a feature change)? the checkbox in the parent node will update the child node that is located directly under the parent node.

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?) No

closes: https://github.com/wopehq/vue3-tree/issues/115