fix backend switching

[StRigaud]

No description provided.

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 59.57447% with 38 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.75%. Comparing base (dfc44a7) to head (b1cf0ba).

Files with missing lines	Patch %	Lines
pyclesperanto/_operators.py	9.09%	20 Missing ⚠️
pyclesperanto/_array.py	83.33%	10 Missing ⚠️
pyclesperanto/_backend.py	0.00%	6 Missing ⚠️
pyclesperanto/_core.py	50.00%	2 Missing ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #385      +/-   ##
==========================================
- Coverage   83.38%   82.75%   -0.63%     
==========================================
  Files          24       24              
  Lines        2064     2082      +18     
==========================================
+ Hits         1721     1723       +2     
- Misses        343      359      +16     

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