MNT: add explicit configuration for setuptools-scm to pyproject.toml

Author: neutrinoceros

pyproject.toml

@@ -1,7 +1,7 @@
 [build-system]
 requires = [
     "setuptools>=61.2",
-    "setuptools_scm>=6.2",
+    "setuptools_scm>=8.0.0",
     "wheel",
     "jinja2>=2.10.3",
     "numpy>=2.0.0rc1",
@@ -47,6 +47,9 @@ include-package-data = false
 exclude = ["erfa._dev"]
 namespaces = false
 
+[tool.setuptools_scm]
+version_file = "erfa/_version.py"
+
 [tool.pytest.ini_options]
 minversion = "4.6"
 testpaths = ["erfa", "docs", "README.rst"]