Make PST GPU-compatible

[efaulhaber]

As requested by @LasNikas.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 54.54545% with 5 lines in your changes missing coverage. Please review.

Project coverage is 70.74%. Comparing base (6d04215) to head (41b0096). Report is 56 commits behind head on main.

Files with missing lines	Patch %	Lines
src/callbacks/particle_shifting.jl	0.00%	5 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #813      +/-   ##
==========================================
+ Coverage   70.53%   70.74%   +0.21%     
==========================================
  Files          96      106      +10     
  Lines        5976     6710     +734     
==========================================
+ Hits         4215     4747     +532     
- Misses       1761     1963     +202     

Flag	Coverage Δ
unit	70.74% <54.54%> (+0.21%)	:arrow_up:

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[LasNikas]

\run-gpu-tests

[svchb]

/run-gpu-tests