Get setuptools-scm working again

run_af2/pyproject.toml

@@ -17,8 +17,8 @@ write_to = "src/run_af2/version.py"
 
 [build-system]
 requires = [
-    "setuptools>=56",
+    "setuptools==56",
     "wheel",
-    "setuptools_scm[toml]>=6.0"
+    "setuptools_scm==6.0"
 ]
 build-backend = "setuptools.build_meta"