Lower version guard in check_ast_node to Python 3.12 (#1355)

The version guard for deprecated AST node types (Num, Str, Bytes,
Ellipsis, NameConstant) currently activates only on Python >= 3.14,
where these types are removed. However, these types emit
DeprecationWarning on Python 3.12 and 3.13 when accessed via getattr.

Lower the guard from (3, 14) to (3, 12) to avoid triggering
DeprecationWarning on Python 3.12-3.13. The early return behavior is
identical: the node name is known-valid and is returned directly,
skipping the unnecessary getattr call.

Author: rcgray

bandit/core/utils.py

@@ -370,9 +370,9 @@ def parse_ini_file(f_loc):
 def check_ast_node(name):
     "Check if the given name is that of a valid AST node."
     try:
-        # These ast Node types don't exist in Python 3.14, but plugins may
-        # still check on them.
-        if sys.version_info >= (3, 14) and name in (
+        # These ast Node types were deprecated in Python 3.12 and removed
+        # in Python 3.14, but plugins may still check on them.
+        if sys.version_info >= (3, 12) and name in (
             "Num",
             "Str",
             "Ellipsis",