[ast.Str] Use ast.Constant instead pending removal in python 3.14

[Pierre-Sassoulas]

Pytest start raising deprecation warning in its own code when launched with python 3.12:

  File "/home/runner/work/astroid/astroid/venv/lib/python3.12/site-packages/_pytest/assertion/rewrite.py", line 683, in run
    and isinstance(item.value, ast.Str)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.0-beta.1/x64/lib/python3.12/ast.py", line 555, in __instancecheck__
    warnings._deprecated(
  File "/opt/hostedtoolcache/Python/3.12.0-beta.1/x64/lib/python3.12/warnings.py", line 529, in _deprecated
    warn(msg, DeprecationWarning, stacklevel=3)
DeprecationWarning: ast.Str is deprecated and will be removed in Python 3.14; use ast.Constant instead

See https://github.com/pylint-dev/astroid/actions/runs/5196979689/jobs/9371270546?pr=2199. I'm not sure if ast.Str and ast.Constant are really equivalent so I'm opening the PR to launch the CI and see.

[Pierre-Sassoulas]

How about waiting 3 weeks for python 3.7 EOL 😄 ?

[The-Compiler]

Thanks for the contribution! However, this is already being fixed as part of #10894, so I'm closing this as a duplicate.