Fix problem in dependabot config, yarn is not a valid package-ecosystem, we can try npm
Fix problem in dependabot config, yarn is not a valid package-ecosystem, we can try npm

mkllnk/openfoodnetwork,mkllnk/openfoodnetwork,openfoodfoundation/openfoodnetwork,lin-d-hop/openfoodnetwork,mkllnk/openfoodnetwork,openfoodfoundation/openfoodnetwork,Matt-Yorkley/openfoodnetwork,lin-d-hop/openfoodnetwork,Matt-Yorkley/openfoodnetwork,mkllnk/openfoodnetwork,openfoodfoundation/openfoodnetwork,openfoodfoundation/openfoodnetwork,lin-d-hop/openfoodnetwork,lin-d-hop/openfoodnetwork,Matt-Yorkley/openfoodnetwork,Matt-Yorkley/openfoodnetwork