🐛 Fix setuptools version compatibility with Python 3.7

- Lowered the required version of setuptools to be compatible with Python 3.7.
- Resolved the error: "No matching distribution found for setuptools>=70.0.0" in the GitHub Actions workflow.

pyproject.toml

@@ -2,7 +2,7 @@
 line-length = 79
 
 [build-system]
-requires = ["setuptools>=70.0.0", "wheel"]
+requires = ["setuptools>=68.0.0", "wheel"]
 build-backend = "setuptools.build_meta"
 
 [project]