Fix tests

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

priv/repo/migrations/20180628142835_revert_alter_event_timestamps.exs

@@ -1,15 +1,15 @@
-defmodule Mobilizon.Repo.Migrations.AlterEventTimestampsToDateTimeWithTimeZone do
+defmodule Mobilizon.Repo.Migrations.RevertAlterEventTimestampsToDateTimeWithTimeZone do
   use Ecto.Migration
 
   def up do
-    alter table("events") do
+    alter table(:events) do
       modify :inserted_at, :timestamptz
       modify :updated_at, :timestamptz
     end
   end
 
   def down do
-    alter table("events") do
+    alter table(:events) do
       modify :inserted_at, :utc_datetime
       modify :updated_at, :utc_datetime
     end