Replace use of deprecated C Standard library headers in C++ code.

Change-Id: I9fa6630c7e4bdb2897df34d417635d8c7d8253bc
Signed-off-by: Tyler Chatow <tchatow@gmail.com>
diff --git a/frc971/control_loops/state_feedback_loop.h b/frc971/control_loops/state_feedback_loop.h
index 50edf0d..4250df2 100644
--- a/frc971/control_loops/state_feedback_loop.h
+++ b/frc971/control_loops/state_feedback_loop.h
@@ -1,8 +1,7 @@
 #ifndef FRC971_CONTROL_LOOPS_STATE_FEEDBACK_LOOP_H_
 #define FRC971_CONTROL_LOOPS_STATE_FEEDBACK_LOOP_H_
 
-#include <assert.h>
-
+#include <cassert>
 #include <chrono>
 #include <memory>
 #include <utility>