Fix flaky db warnings test

[fatkodima]

Fixes a flaky test from https://buildkite.com/rails/rails/builds/102185#018bf92f-d565-4801-9355-953b2132e421.

[jonathanhefner]

This file does not include require "models/post", so we would also need to add that to use Post.

But this test seems like the odd one out. All the other tests use SELECT 1 + "foo", even the "db_warnings_action allows a list of warnings to ignore" right above. So why don't we make this test match the others instead?

  test "db_warnings_action allows a list of codes to ignore" do
    with_db_warnings_action(:raise, ["1292"]) do
      result = @connection.execute('SELECT 1 + "foo"')

      assert_equal [1], result.to_a.first
    end
  end

[fatkodima]

👍 Changed.

[jonathanhefner]

Thank you, @fatkodima! 🧪