Philippe 10/09/2021: OpenACC: add detection of OpenACC versions 3.0 and 3.1

src/LIB/SURCOUCHE/src/mode_mnh_world.f90

@@ -104,6 +104,10 @@ CONTAINS
               PRINT *,"Using OpenACC 2.6"
             case ( 201811 )
               PRINT *,"Using OpenACC 2.7"
+            case ( 201911 )
+              PRINT *,"Using OpenACC 3.0"
+            case ( 202011 )
+              PRINT *,"Using OpenACC 3.1"
             case default
               PRINT *,"Using OpenACC (unknown version)"
           end select