Update fast_atof.h

Fix include brackets.

code/fast_atof.h

@@ -26,7 +26,7 @@
 #ifdef _MSC_VER
 #  include <stdint.h>
 #else
-#include <assimp/Compiler/pstdint.h"
+#  include <assimp/Compiler/pstdint.h>
 #endif
 
 namespace Assimp