PHPUnit 10 Migration (#1302)

* Bump PHPUnit dependencies

* Set return type of base TestCase methods

From the [PHPUnit 8 release notes][1], the `TestCase` methods below now declare a `void` return type:

- `setUpBeforeClass()`
- `setUp()`
- `assertPreConditions()`
- `assertPostConditions()`
- `tearDown()`
- `tearDownAfterClass()`
- `onNotSuccessfulTest()`

[1]: https://phpunit.de/announcements/phpunit-8.html

* Ignore PHPUnit cache folder

* Adopt PHP attributes in test classes

* Declare data providers as `static`

* Add return types to test methods

* Define test classes as `final`

* Migrate phpunit.xml to phpunit 10

* Correct phpunit attribute class name

* Rename base test class

* Restructure test folders

* Fix test image paths

* Only set rules for php files in .editorconfig

* Remove php unit flag in local test env

---------

Co-authored-by: Shift <shift@laravelshift.com>

tests/Unit/Geometry/Factories/CircleFactoryTest.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Unit\Geometry\Factories;
+
+use Intervention\Image\Geometry\Ellipse;
+use Intervention\Image\Geometry\Factories\CircleFactory;
+use Intervention\Image\Geometry\Point;
+use Intervention\Image\Tests\BaseTestCase;
+
+final class CircleFactoryTest extends BaseTestCase
+{
+    public function testFactoryCallback(): void
+    {
+        $factory = new CircleFactory(new Point(1, 2), function ($circle) {
+            $circle->background('fff');
+            $circle->border('ccc', 10);
+            $circle->radius(100);
+            $circle->diameter(1000);
+        });
+
+        $circle = $factory();
+        $this->assertInstanceOf(Ellipse::class, $circle);
+        $this->assertTrue($circle->hasBackgroundColor());
+        $this->assertEquals('fff', $circle->backgroundColor());
+        $this->assertEquals('ccc', $circle->borderColor());
+        $this->assertEquals(10, $circle->borderSize());
+        $this->assertEquals(1000, $circle->width());
+        $this->assertEquals(1000, $circle->height());
+    }
+}