BUG: The bytes returned by cuda StreamReader may leads to deserialization failed

[ChengjieLi28]

What do these changes do?

When I adapt copy_to to xorbits, xoscar cannot deserialize the transferred cupy object. In xorbits, all the cuda object will use rmm.DeviceBuffer-based object to store actual data. But in xoscar, the result of deserialization could be the organic bytes object. I think using rmm.DeviceBuffer is definitely correct.

Check code requirements

• [ ] tests added / passed (if needed)
• [ ] Ensure all linting tests pass

[codecov[bot]]

Codecov Report

Merging #40 (a23008e) into main (7531e22) will decrease coverage by 0.15%. The diff coverage is n/a.

@@            Coverage Diff             @@
##             main      #40      +/-   ##
==========================================
- Coverage   93.79%   93.64%   -0.15%     
==========================================
  Files          43       43              
  Lines        3399     3399              
  Branches      675      675              
==========================================
- Hits         3188     3183       -5     
- Misses        139      145       +6     
+ Partials       72       71       -1     

Flag	Coverage Δ
unittests	93.49% <ø> (-0.15%)	:arrow_down:

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Impacted Files	Coverage Δ
python/xoscar/backends/communication/utils.py	100.00% <ø> (ø)

... and 2 files with indirect coverage changes