Limit moto to <5.0.0 until the breaking issues are fixed

[Nusnus]

Yesterday, v5.0.0 was released, which introduces an import error.
Limiting to below this version to return stability until it can receive focus for fixing.

[Nusnus]

============================================================================= ERRORS ==============================================================================
___________________________________________________________ ERROR collecting t/unit/backends/test_s3.py ___________________________________________________________
ImportError while importing test module '/home/developer/celery/t/unit/backends/test_s3.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
../.pyenv/versions/3.12.1/lib/python3.12/importlib/__init__.py:90: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
t/unit/backends/test_s3.py:6: in <module>
    from moto import mock_s3
E   ImportError: cannot import name 'mock_s3' from 'moto' (/home/developer/celery/.tox/3.12-unit/lib/python3.12/site-packages/moto/__init__.py). Did you mean: 'mock_aws'?
======================================================================== warnings summary =========================================================================

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b1c8b28) 81.22% compared to head (bdd043a) 81.22%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8820   +/-   ##
=======================================
  Coverage   81.22%   81.22%           
=======================================
  Files         148      148           
  Lines       18523    18523           
  Branches     3165     3165           
=======================================
  Hits        15045    15045           
  Misses       3191     3191           
  Partials      287      287           

Flag	Coverage Δ
unittests	81.20% <ø> (ø)

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