Fix diagnose errors

[adriankumpf]

This fixes an error that occurred when running EctoPSQLExtras.diagnose/1 on Postgres 11.16:

10:49:56.541 [warning] Elixir.EctoPSQLExtras.DiagnoseLogic
** (MatchError) no match of right hand side value: :error
    (ecto_psql_extras 0.7.9) lib/ecto_psql_extras/diagnose_logic.ex:133: anonymous fn/1 in EctoPSQLExtras.DiagnoseLogic.null_indexes/1
    (elixir 1.14.2) lib/enum.ex:4197: Enum.filter_list/2
    (elixir 1.14.2) lib/enum.ex:4198: Enum.filter_list/2
    (ecto_psql_extras 0.7.9) lib/ecto_psql_extras/diagnose_logic.ex:132: EctoPSQLExtras.DiagnoseLogic.null_indexes/1
    (ecto_psql_extras 0.7.9) lib/ecto_psql_extras/diagnose_logic.ex:28: EctoPSQLExtras.DiagnoseLogic.run/1
    (ecto_psql_extras 0.7.9) lib/ecto_psql_extras.ex:121: EctoPSQLExtras.query/3
    (elixir 1.14.2) src/elixir.erl:309: anonymous fn/4 in :elixir.eval_external_handler/1
    (stdlib 4.1.1) erl_eval.erl:748: :erl_eval.do_apply/7

This was caused by EctoPSQLExtras.null_indexes/2 returning the following row:

[465344, "line_item_corrections_line_item_id_index", "1424 kB", true, "line_item_id", "    .07%", "972 bytes"]

Note the " .07%".

format_value/1 also failed because for some reason the tuple {string, :string} did not contain a string but an integer (465344).

[pawurb]

👍