Fix xfluid test

Author: eulovi

tests/input_files/xfluid_forward_facing_step_stationary_NavSlip_eps1.6_16x16_NIT_altgeogeneration.4C.yaml

@@ -54,7 +54,7 @@ RESULT DESCRIPTION:
       NODE: 3461
       QUANTITY: "vely"
       VALUE: 0.00668161125310244
-      TOLERANCE: 1e-13
+      TOLERANCE: 1e-12
   - XFLUID:
       DIS: "fluid"
       NODE: 3461