Fix test mocks to patch actual module locations

Instead of re-exporting functions just to satisfy mocks, fix the tests
to mock the correct module where the functions actually live.

- Updated test_read_pyproject_with_given_definition to patch vcs_versioning._toml.read_toml_content instead of setuptools_scm._integration.pyproject_reading.read_toml_content
- Removed unnecessary re-export of read_toml_content

All tests now passing: 329 passed, 10 skipped, 1 xfailed

Author: RonnyPfannschmidt

testing/test_pyproject_reading.py

@@ -114,7 +114,7 @@ def test_invalid_requirement_string(self) -> None:
 def test_read_pyproject_with_given_definition(monkeypatch: pytest.MonkeyPatch) -> None:
     """Test that read_pyproject reads existing files correctly."""
     monkeypatch.setattr(
-        "setuptools_scm._integration.pyproject_reading.read_toml_content",
+        "vcs_versioning._toml.read_toml_content",
         Mock(side_effect=FileNotFoundError("this test should not read")),
     )