Fix missing transfer to device in ProjectedGradientDescentPyTorch

[beat-buesser]

Description

This pull request fixes a missing transfer to device in ProjectedGradientDescentPyTorch.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.41%. Comparing base (fd63952) to head (d794c1f).
Report is 2 commits behind head on dev_1.19.1.

Additional details and impacted files

@@             Coverage Diff             @@
##           dev_1.19.1    #2558   +/-   ##
===========================================
  Coverage       85.41%   85.41%           
===========================================
  Files             334      334           
  Lines           31001    31001           
  Branches         5300     5300           
===========================================
+ Hits            26478    26481    +3     
+ Misses           3055     3053    -2     
+ Partials         1468     1467    -1     

Files with missing lines	Coverage Δ
...ient_descent/projected_gradient_descent_pytorch.py	95.86% <ø> (ø)

... and 2 files with indirect coverage changes

[kieranfraser]

LGTM - tested on a GPU enabled instance and have replicated the issue error and confirmed this PR fixes the issue.