Fix deep copy of gates.M in Circuit.copy()

[BrunoLiegiBastonLiegi]

Bugfix to #1249 .

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.

[renatomello]

It's best to fix the tests here only after #1202 is merged.

[renatomello]

@BrunoLiegiBastonLiegi unrelated: do you know why this is failing? https://github.com/qiboteam/qibo/actions/runs/8281358719/job/22660149672

[BrunoLiegiBastonLiegi]

@BrunoLiegiBastonLiegi unrelated: do you know why this is failing? https://github.com/qiboteam/qibo/actions/runs/8281358719/job/22660149672

I would say that the lock needs to be regenerated, after the PytorchBackend merge you need torch installed but if you only have the pyproject.toml updated it's not gonna install torch I believe, but I might be wrong.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.94%. Comparing base (3474d5e) to head (8208831).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1250      +/-   ##
==========================================
- Coverage   99.95%   99.94%   -0.01%     
==========================================
  Files          73       73              
  Lines       10636    10638       +2     
==========================================
+ Hits        10631    10632       +1     
- Misses          5        6       +1     

Flag	Coverage Δ
unittests	99.94% <100.00%> (-0.01%)	⬇️

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