fix(print-cost-model): add missing LinearInXAndY case to renderModel

Add LinearInXAndY case to the renderModel function in print-cost-model
executable to handle the linear_in_x_and_y costing function type that
was introduced for valueContains builtin.

This addresses Kenneth's comment about the missing case in the
print-cost-model executable.

Fixes: #7476 (comment)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: Unisay

plutus-core/cost-model/print-cost-model/Main.hs

@@ -137,6 +137,7 @@ renderModel =
     QuadraticInXAndY f -> [renderTwoVariableQuadraticFunction f "x" "y"]
     ExpModCost f -> [renderExpModCostingFunction f "y" "z"]
     LinearInMaxYZ f -> [renderLinearFunction f "max(y,z)"]
+    LinearInXAndY f -> [renderTwoVariableLinearFunction f "x" "y"]
     LinearInYAndZ f -> [renderTwoVariableLinearFunction f "y" "z"]
     LiteralInYOrLinearInZ f ->
       [ "if y==0"