Change models, new migrations, fix front and make tests work

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/eventos/groups/member.ex

@@ -0,0 +1,22 @@
+defmodule Eventos.Groups.Member do
+  use Ecto.Schema
+  import Ecto.Changeset
+  alias Eventos.Groups.{Member, Group}
+  alias Eventos.Accounts.Account
+
+
+  schema "members" do
+    field :role, :integer
+    belongs_to :group, Group
+    belongs_to :account, Account
+
+    timestamps()
+  end
+
+  @doc false
+  def changeset(%Member{} = member, attrs) do
+    member
+    |> cast(attrs, [:role])
+    |> validate_required([:role])
+  end
+end