Remove dependency of proj_matrix during scoring (#61)

finalize feature deletes the proj_matrix, but basic projector assumes it exists. remove dependency.

trak/projectors.py

@@ -254,7 +254,7 @@ def free_memory(self):
     def get_generator_states(self):
         self.generator_states = []
         self.seeds = []
-        self.jl_size = self.proj_matrix.numel()
+        self.jl_size = self.grad_dim * self.block_size 
 
         for i in range(self.num_blocks):
             s = self.seed + int(1e3) * i + int(1e5) * self.model_id