Fix confusing message

The compatibility check makes more specific sense on plugin level.

src/include-bash/sfpi.sh

@@ -116,7 +116,7 @@ sfpi__import() {
         return 3
     }
     sfpi__is_compat "$plg" || {
-        warn "module not compatible: $mod"
+        warn "plugin not compatible: $mod"
         return 3
     }
     shellfu import "$mod"