detect and update output for OpenMP version 5.1

src/info.cpp

@@ -1356,8 +1356,10 @@ std::string Info::get_openmp_info()
 // Supported OpenMP version corresponds to the release date of the
 // specifications as posted at https://www.openmp.org/specifications/
 
-#if _OPENMP > 201811
-  return "OpenMP newer than version 5.0";
+#if _OPENMP > 202011
+  return "OpenMP newer than version 5.1";
+#elif _OPENMP == 202011
+  return "OpenMP 5.1";
 #elif _OPENMP == 201811
   return "OpenMP 5.0";
 #elif _OPENMP == 201611