Fix NFRValidator import in test_runtime_dynamics.py

Co-authored-by: fermga <203334638+fermga@users.noreply.github.com>

Author: Copilot

tests/math_integration/test_runtime_dynamics.py

@@ -10,9 +10,9 @@
     CoherenceOperator,
     HilbertSpace,
     MathematicalDynamicsEngine,
-    NFRValidator,
     make_frequency_operator,
 )
+from tnfr.validation import NFRValidator
 from tnfr.node import NodeNX
 from tnfr.operators.definitions import (
     Coherence,