fix Moment.resolve_parameter not resolving all the expressions

Fixes #6778
Fix Moment.resolve_parameters to properly resolve symbolic expressions

    Changed equality check from '!=' to 'is not' to handle cases where symbolic parameters are equivalent but not identical objects

    Ensured that the method returns a new object only when a variable is resolved, maintaining efficient behavior.

    Tested the fix with existing cases for Rx, Ry, and Rz gates to confirm correct behavior when parameters are resolved or remain unchanged.

cirq-core/cirq/circuits/moment.py

@@ -275,7 +275,7 @@ def _resolve_parameters_(
         resolved_ops: List['cirq.Operation'] = []
         for op in self:
             resolved_op = protocols.resolve_parameters(op, resolver, recursive)
-            if resolved_op != op:
+            if resolved_op is not op:
                 changed = True
             resolved_ops.append(resolved_op)
         if not changed: