move specification of build dependency on setuptools-scm from setup.py to pyproject.toml

pyproject.toml

@@ -0,0 +1,3 @@
+[build-system]
+# https://github.com/pypa/setuptools-scm/tree/v7.1.0?tab=readme-ov-file#pyprojecttoml-usage
+requires = ["setuptools>=45", "setuptools_scm[toml]>=6.2"]

setup.py

@@ -44,6 +44,5 @@ setuptools.setup(
     # >=3.8 walrus operator
     python_requires=">=3.9",  # <3.9 untested
     install_requires=[],
-    setup_requires=["setuptools_scm"],
     tests_require=["pytest"],
 )