Add judging condition for function areAlreadyProcessed

[Jerry-SEU]

Hello!
I use DExecutor for task scheduling, and I find that in some case, one node is skiped, but it's out coming node will still be executed. After debug for hours, I find that modifing the code here may be helpful.
I changed this place to "return this.processedNodes.stream().filter(Node::isSuccess).collect(Collectors.toSet()).containsAll(nodes);",and it worked.

dexecutor-core/src/main/java/com/github/dexecutor/core/DefaultDexecutorState.java

Line 122 in f474b91

return this.processedNodes.containsAll(nodes);

[mnadeem]

Please create a pull request