internal-comp-loader: fix `WpSpaJson` memory leak
Previously, the `deps` variable was reused for parsing
the required and wanted dependencies of a component,
which lead to the old value allocated here:
if (wp_spa_json_object_get (json, "requires", "J", &deps, NULL)) {
being leaked when a bit later
if (wp_spa_json_object_get (json, "wants", "J", &deps, NULL)) {
succeeded.
Fix that by using two separate variables.