chore: upgrade to L9

BREAKING CHANGE: This commit updates the Laravel framework to version 9. Additionally, it also updates outdated and abandoned dependencies in the composer.json file.

The resources/lang directory has also been moved to the repository's root directory.

lang/en/auth.php

@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * Copyright © 2020 Miguel Nogueira
+ *
+ *   This file is part of Raspberry Staff Manager.
+ *
+ *     Raspberry Staff Manager is free software: you can redistribute it and/or modify
+ *     it under the terms of the GNU General Public License as published by
+ *     the Free Software Foundation, either version 3 of the License, or
+ *     (at your option) any later version.
+ *
+ *     Raspberry Staff Manager is distributed in the hope that it will be useful,
+ *     but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *     GNU General Public License for more details.
+ *
+ *     You should have received a copy of the GNU General Public License
+ *     along with Raspberry Staff Manager.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+return [
+
+    /*
+    |--------------------------------------------------------------------------
+    | Authentication Language Lines
+    |--------------------------------------------------------------------------
+    |
+    | The following language lines are used during authentication for various
+    | messages that we need to display to the user. You are free to modify
+    | these language lines according to your application's requirements.
+    |
+    */
+
+    'failed' => 'These credentials do not match our records.',
+    'throttle' => 'Too many login attempts. Please try again in :seconds seconds.',
+
+];