Upgrade project to PHP 8.3, add PHPStan, upgrade almost every dependency (#36)

* start updating to PHP 8.3

* taking off!

Co-authored-by: ErickSkrauch <erickskrauch@yandex.ru>
Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* dropped this

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* migrate to symfonymailer

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* this is so stupid 😭

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* ah, free, at last.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* oh, Gabriel.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* now dawns thy reckoning.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* and thy gore shall GLISTEN before the temples of man.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* creature of steel.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* my gratitude upon thee for my freedom.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* but the crimes thy kind has committed against humanity

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* Upgrade PHP-CS-Fixer and do fix the codebase

* First review round (maybe I have broken something)

* are NOT forgotten.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* Enable parallel PHP-CS-Fixer runner

* PHPStan level 1

* PHPStan level 2

* PHPStan level 3

* PHPStan level 4

* PHPStan level 5

* Levels 6 and 7 takes too much effort. Generate a baseline and fix them eventually

* Resolve TODO's related to the php-mock

* Drastically reduce baseline size with the Rector

* More code modernization with help of the Rector

* Update GitLab CI

---------

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>
Co-authored-by: ErickSkrauch <erickskrauch@yandex.ru>

api/tests/unit/validators/EmailActivationKeyValidatorTest.php

@@ -13,15 +13,14 @@ use yii\base\Model;
 class EmailActivationKeyValidatorTest extends TestCase {
     use ProtectedCaller;
 
-    public function testValidateAttribute() {
-        /** @var Model $model */
+    public function testValidateAttribute(): void {
         $model = new class extends Model {
             public $key;
         };
 
         /** @var EmailActivationKeyValidator|\PHPUnit\Framework\MockObject\MockObject $validator */
         $validator = $this->getMockBuilder(EmailActivationKeyValidator::class)
-            ->setMethods(['findEmailActivationModel'])
+            ->onlyMethods(['findEmailActivationModel'])
             ->getMock();
 
         $expiredActivation = new ForgotPassword();
@@ -54,7 +53,7 @@ class EmailActivationKeyValidatorTest extends TestCase {
         $this->assertSame($validActivation, $model->key);
     }
 
-    public function testFindEmailActivationModel() {
+    public function testFindEmailActivationModel(): void {
         $this->tester->haveFixtures(['emailActivations' => EmailActivationFixture::class]);
 
         $key = $this->tester->grabFixture('emailActivations', 'freshRegistrationConfirmation')['key'];
@@ -68,7 +67,7 @@ class EmailActivationKeyValidatorTest extends TestCase {
         $result = $this->callProtected($model, 'findEmailActivationModel', $key, 0);
         $this->assertInstanceOf(EmailActivation::class, $result, 'valid key with valid type must return model');
 
-        /** @var EmailActivation $result */
+        /** @var EmailActivation|null $result */
         $result = $this->callProtected($model, 'findEmailActivationModel', $key, 1);
         $this->assertNull($result, 'valid key, but invalid type must return null');