** (DBConnection.OwnershipError) cannot find ownership process for #PID

When attempting to create/run a test that inserts data:

```elixir
defmodule UseragentTest do
use ExUnit.Case
alias Hits.Useragent

test "Useragent.insert" do
useragent = "Mozilla/5.0 (Windows; Windows NT 5.0; rv:1.1) Gecko/20020826"
ip = "127.0.0.1"
useragent_id = Useragent.insert(%Useragent{name: useragent, ip: ip})

IO.inspect(useragent_id, label: "useragent_id")
end

end
```
attempting to run it with the command:
```
mix test test/useragent_test.exs
```
I get the following error:

```
1) test Useragent.insert (UseragentTest)
test/useragent_test.exs:8
** (DBConnection.OwnershipError) cannot find ownership process for #PID<0.390.0>.

When using ownership, you must manage connections in one
of the four ways:

* By explicitly checking out a connection
* By explicitly allowing a spawned process
* By running the pool in shared mode
* By using :caller option with allowed process

The first two options require every new process to explicitly
check a connection out or be allowed by calling checkout or
allow respectively.

The third option requires a {:shared, pid} mode to be set.
If using shared mode in tests, make sure your tests are not
async.

The fourth option requires [caller: pid] to be used when
checking out a connection from the pool. The caller process
should already be allowed on a connection.

If you are reading this error, it means you have not done one
of the steps above or that the owner process has crashed.

See Ecto.Adapters.SQL.Sandbox docs for more information.
code: useragent_id = Useragent.insert(%Useragent{name: useragent, ip: ip})
stacktrace:
(ecto_sql) lib/ecto/adapters/sql.ex:602: Ecto.Adapters.SQL.raise_sql_call_error/1
(ecto_sql) lib/ecto/adapters/sql.ex:538: Ecto.Adapters.SQL.execute/5
(ecto) lib/ecto/repo/queryable.ex:153: Ecto.Repo.Queryable.execute/4
(ecto) lib/ecto/repo/queryable.ex:18: Ecto.Repo.Queryable.all/3
(ecto) lib/ecto/repo/queryable.ex:67: Ecto.Repo.Queryable.one/3
(hits) lib/hits/useragent.ex:31: Hits.Useragent.insert/1
test/useragent_test.exs:11: (test)
```

Obviously the `Useragent.insert` works when I run the app `mix phx.server` ...
But the test does not run because it does not have ownership of the connection ... 😞

Start by running mix test test/useragent_test.exs and inspect test/useragent_test.exs alongside Hits.Useragent.insert/1 in lib/hits/useragent.ex. Read the Ecto.Adapters.SQL.Sandbox documentation to understand the missing ownership setup. Done means the test inserts the data without DBConnection.OwnershipError.

Written by the indexing model from the issue text.