Solve typo on day 25 puzzle

Author: Flashky

src/main/java/com/adventofcode/flashk/day25/Snowverload.java

@@ -22,6 +22,7 @@ public Snowverload(List<String> inputs) {
             graph.addVertex(leftVertex);
             for(String rightVertex : rightVertexes) {
                 graph.addVertex(rightVertex);
+                graph.addEdge(leftVertex, rightVertex);
             }
         }