[T/THM] Slightly relax conv. tolerance

The generated TRM project in the SaturatedPointheatsource.ipynb notebook
does not converge otherwise.

Tests/Data/ThermoRichardsMechanics/PointHeatSource/point_heat_source_2D.prj

@@ -142,7 +142,7 @@
                 <convergence_criterion>
                     <type>PerComponentDeltaX</type>
                     <norm_type>NORM2</norm_type>
-                    <reltols>1e-15 1e-15 1e-15 1e-15</reltols>
+                    <reltols>1e-15 1e-14 5e-15 5e-15</reltols>
                 </convergence_criterion>
                 <time_discretization>
                     <type>BackwardEuler</type>