Thanks for your reply Thomas.
I changed two lines in my Dataset class:
...
data = np.asarray(data).astype(np.float32).reshape(1,n, n)
...
      y = np.asarray(y).astype(np.float32).reshape(n,)
...

And the error is essentially the same but float32-version of it.
Output:
0.0
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-127-b3db64ef4a36> in <module>
     13 
     14 print(train_data.__getitem__(1)[1][1])
---> 15 print(train_data_normal.__getitem__(1)[1][1])
     16 
     17 # trainLoader = DataLoader(train_data, batch_size=128, shuffle=True)
.....
.....
.....
TypeError: Input type float32 is not supported