timescaledb_toolkit: Fix license metadata to TSL license.

    homepage = "https://github.com/timescale/timescaledb-toolkit";

    maintainers = with maintainers; [ typetetris ];

    platforms = postgresql.meta.platforms;

    license = licenses.asl20;

    license = licenses.tsl;

    # as it needs to be used with timescaledb, simply use the condition from there

    broken = stdenv.isDarwin;