gpu fourierembedding (#313)

Adding gpu to fourier embedding

pina/model/layers/embedding.py

@@ -246,7 +246,7 @@ class FourierFeatureEmbedding(torch.nn.Module):
         :rtype: torch.Tensor
         """
         # compute random matrix multiplication
-        out = torch.mm(x, self._matrix)
+        out = torch.mm(x, self._matrix.to(device=x.device, dtype=x.dtype))
         # return embedding
         return torch.cat(
             [torch.cos(2 * torch.pi * out), torch.sin(2 * torch.pi * out)],