Fix typo (found by codespell)

Signed-off-by: Stefan Weil <sw@weilnetz.de>

clstm.h

@@ -199,7 +199,7 @@ void set_derivs(Network net, Float *params, int total, int gpu = -1);
 void get_derivs(Network net, Float *params, int total, int gpu = -1);
 
 // get the number of internal state variables for the network; this
-// changes after every foward propagation pass; note that this includes
+// changes after every forward propagation pass; note that this includes
 // both numerical values and the shapes of internal tensors
 int n_states(Network net);