Fix typo. indepdendent -> independent

Change-Id: I7f04f5e82a6e47e8d22c902744729f3f6d93dee8

internal/ceres/graph_algorithms_test.cc

diff --git a/internal/ceres/graph_algorithms_test.cc b/internal/ceres/graph_algorithms_test.cc
index ab74a2d..1071488 100644
--- a/internal/ceres/graph_algorithms_test.cc
+++ b/internal/ceres/graph_algorithms_test.cc
@@ -90,7 +90,7 @@
   //    4-0-2
   //      |
   //      3
-  // 1, 2, 3, 4 should be in the indepdendent set.
+  // 1, 2, 3, 4 should be in the independent set.
   vector<int> ordering;
   int independent_set_size = IndependentSetOrdering(graph, &ordering);
   EXPECT_EQ(independent_set_size, 4);