Add fixes for GPU tests

[SeanNaren]

What does this PR do?

Attempt to try get GPU tests green!

Before submitting

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• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests? [not needed for typos/docs]
• Did you verify new and existing tests pass locally with your changes?
• If you made a notable change (that affects users), did you update the CHANGELOG?

PR review

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Anyone in the community is free to review the PR once the tests have passed.
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[codecov]

Codecov Report

Merging #714 (2286093) into master (47eb2aa) will increase coverage by 0.64%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #714      +/-   ##
==========================================
+ Coverage   72.17%   72.82%   +0.64%     
==========================================
  Files         121      121              
  Lines        7550     7550              
==========================================
+ Hits         5449     5498      +49     
+ Misses       2101     2052      -49     

Flag	Coverage Δ
cpu	72.82% <100.00%> (+0.64%)	⬆️
pytest	72.82% <100.00%> (+0.64%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pl_bolts/callbacks/verification/base.py	100.00% <100.00%> (ø)
pl_bolts/models/rl/advantage_actor_critic_model.py	97.70% <100.00%> (ø)
pl_bolts/models/rl/dqn_model.py	80.44% <100.00%> (ø)
pl_bolts/models/rl/reinforce_model.py	89.39% <100.00%> (ø)
...l_bolts/models/rl/vanilla_policy_gradient_model.py	93.44% <100.00%> (ø)
pl_bolts/datasets/mnist_dataset.py	87.50% <0.00%> (-4.17%)	⬇️
..._bolts/models/self_supervised/moco/moco2_module.py	59.42% <0.00%> (ø)
...l_bolts/models/self_supervised/byol/byol_module.py	51.06% <0.00%> (+28.72%)	⬆️
pl_bolts/callbacks/byol_updates.py	100.00% <0.00%> (+31.81%)	⬆️
... and 1 more

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