Fix gpu unit test.

[hunghaoti]

1. Fix Lanczos Gnd unit test cause from putblock using different devices.
2. Skip ExpM for gpu test since Eig still not implemted, which is needed to do the exponential.
3. cuda svd cannot give the correct answer if almost elements are zeros. So we skip Svd U1_zeros tests.
4. The answer of Svd_truncate3 is not correct also cause from the above issue. So I delete it.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 23.58%. Comparing base (50490b4) to head (6a00436).
Report is 3 commits behind head on dev-master.

Additional details and impacted files

@@             Coverage Diff             @@
##           dev-master     #545   +/-   ##
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  Coverage       23.58%   23.58%           
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  Files             211      211           
  Lines           44926    44926           
  Branches        14018    14018           
===========================================
  Hits            10595    10595           
  Misses          32664    32664           
  Partials         1667     1667           

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[IvanaGyro]

Just leave a reference. The third problem was addressed in #505.

[IvanaGyro]

Does the first problem imply there is a bug in the function to put blocks while the device is the GPU?

[IvanaGyro]

Feel free to close the conversations to merge the PR.

[hunghaoti]

Does the first problem imply there is a bug in the function to put blocks while the device is the GPU?

The first problem cause since we cannot put a Tensor in GPU device to the UniTensor in CPU device. So we just create Tensors in CPU and put it in UniTensor in CPU. And then transfer to GPU finally.