r3.flow: add unit test keyword to test.r3flow (as in test.raster3d.lib), remove hydrology keywords

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@69372 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster3d/r3.flow/test_main.c

@@ -41,8 +41,7 @@ int main(int argc, char *argv[])
     G_gisinit(argv[0]);
     module = G_define_module();
     G_add_keyword(_("raster3d"));
-    G_add_keyword(_("hydrology"));
-    G_add_keyword(_("voxel"));
+    G_add_keyword(_("unit test"));
     module->description = _("Testing flow lines.");
 
     test_opt = G_define_option();