CI: adding support for the N300 gNB + NR-UE testing

-- pipeline is polling the develop-nr branch
  -- new conf file / new scenario files
  -- main python now supports LTE and 5G-NR executables in a Ubuntu/CentOS env

targets/RT/USER/nr-softmodem.c

@@ -1237,6 +1237,8 @@ int main( int argc, char **argv )
 
   // wait for end of program
   printf("TYPE <CTRL-C> TO TERMINATE\n");
+  fflush(stdout);
+  fflush(stderr);
   //getchar();
 
 #if defined(ENABLE_ITTI)