fix path name

Author: AtsushiSakai

tests/test_rrt_star.py

@@ -2,7 +2,7 @@
 import sys
 import os
 sys.path.append(os.path.dirname(os.path.abspath(__file__)) +
-                "/../PathPlanning/RRTStar/")
+                "/../PathPlanning/RRTstar/")
 
 try:
     print(sys.path)