use correct include.

fuzz/assimp_fuzzer.cc

@@ -38,7 +38,7 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ---------------------------------------------------------------------------
 */
-#include <assimp/cimport.h>
+#include <assimp/Importer.hpp>
 #include <assimp/scene.h>
 #include <assimp/postprocess.h>