[Math] fix warning C4819 (unsupported character in current code)

MathLib/Integration/GaussLegendreTet.cpp

@@ -30,7 +30,7 @@ initGLTet3X()
 {
     // Cf. Gellert, M., Harbord, R., 1991. Moderate degree cubature formulas for
     // 3-D tetrahedral finite-element approximations. Communications in Applied
-    // Numerical Methods 7, 487–495. doi:10.1002/cnm.1630070609
+    // Numerical Methods 7, 487-495. doi:10.1002/cnm.1630070609
     const double a = 0.0673422422100983;
     const double b = 0.3108859192633005;
     const double c = 0.7217942490673264;