requirements: add setuptools

setuptools must be present in the requirements, otherwise we have the
following errors:
```
$ make test
...
======================================================================
ERROR: repo_resource.test_check (unittest.loader._FailedTest.repo_resource.test_check)
----------------------------------------------------------------------
ImportError: Failed to import test module: repo_resource.test_check
Traceback (most recent call last):
  File "/usr/local/lib/python3.12/unittest/loader.py", line 396, in _find_test_path
    module = self._get_module_from_name(name)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/unittest/loader.py", line 339, in _get_module_from_name
    __import__(name)
  File "/root/repo_resource/test_check.py", line 16, in <module>
    from . import check
  File "/root/repo_resource/check.py", line 19, in <module>
    from repo_resource import common
  File "/root/repo_resource/common.py", line 27, in <module>
    from repo import main as repo
  File "/usr/local/lib/python3.12/site-packages/repo/main.py", line 48, in <module>
    from repo.subcmds.version import Version
  File "/usr/local/lib/python3.12/site-packages/repo/subcmds/__init__.py", line 18, in <module>
    import pkg_resources
ModuleNotFoundError: No module named 'pkg_resources'
```

Signed-off-by: Julien Masson <[email protected]>

repo_resource/requirements.txt

@@ -1,3 +1,4 @@
+setuptools==74.1.2
 gitrepo==2.32.2
 ssh-agent-setup==2.0.1
 GitPython==3.1.31