replaced a inline return with correct {} block

Author: StathisVeinoglou

src/main/java/com/thealgorithms/graph/GraphTraversal.java

@@ -152,7 +152,9 @@ private static <T> boolean appearsAnywhere(Map<T, List<T>> succ, T node) {
             return true;
         }
         for (List<T> nbrs : succ.values()) {
-            if (nbrs != null && nbrs.contains(node)) return true;
+            if (nbrs != null && nbrs.contains(node)) {
+                return true;
+            }
         }
         return false;
     }