add touchless docker deploys

lib/cannery/repo/migrator.ex

@@ -0,0 +1,18 @@
+defmodule Cannery.Repo.Migrator do
+  use GenServer
+  require Logger
+  
+  def start_link(_) do
+    GenServer.start_link(__MODULE__, [], [])
+  end
+  
+  def init(_) do
+    migrate!()
+    {:ok, nil}
+  end
+  
+  def migrate! do
+    path = Application.app_dir(:cannery, "priv/repo/migrations")
+    Ecto.Migrator.run(Cannery.Repo, path, :up, all: true)
+  end
+end