sdist is missing `tests/__init__.py`

The sdist at PyPI is missing the `tests/__init__.py` file and so testing fails:
```
__________________ ERROR collecting tests/test_compliance.py ___________________
ImportError while importing test module '/data/builds/ul-mass-rebuild/components/python/jmespath/build/amd64-3.14/tests/test_compliance.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/lib/python3.14/importlib/__init__.py:88: in import_module
return _bootstrap._gcd_import(name[level:], package, level)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
tests/test_compliance.py:3: in
from tests import OrderedDict
E ImportError: cannot import name 'OrderedDict' from 'tests' (unknown location)
```