Remove redundant contains check

proxy/src/main/java/com/velocitypowered/proxy/plugin/util/PluginDependencyUtils.java

@@ -43,12 +43,10 @@ public class PluginDependencyUtils {
                 graph.removeEdge(node, candidate);
 
                 if (graph.adjacentNodes(node).isEmpty()) {
-                    if (!noEdges.contains(node)) {
                     noEdges.add(node);
                 }
             }
         }
-        }
 
         if (!graph.edges().isEmpty()) {
             throw new IllegalStateException("Plugin circular dependency found: " + createLoopInformation(graph));