[fix] fix deprecated ast features

Author: the-hampel

python/solid_dmft/dmft_tools/matheval.py

@@ -4,16 +4,19 @@
 import math
 
 
+# Determine numeric/constant node for compatibility across Python versions
+_AST_CONSTANT = getattr(ast, "Constant", None)
+
 class MathExpr(object):
-    allowed_nodes = (
+    # Base allowed nodes (version-agnostic)
+    _base_allowed = (
         ast.Module,
         ast.Expr,
         ast.Load,
         ast.Expression,
         ast.Add,
         ast.Sub,
         ast.UnaryOp,
-        ast.Num,
         ast.BinOp,
         ast.Mult,
         ast.Div,
@@ -32,6 +35,11 @@ class MathExpr(object):
         ast.Name,
     )
 
+    # Extend allowed nodes with version-specific constant node
+    allowed_nodes = _base_allowed + (
+        _AST_CONSTANT if _AST_CONSTANT is not None else ast.Num,
+    )
+
     functions = {
         "abs": abs,
         "complex": complex,