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/CircleTest.php

@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Unit\Geometry;
+
+use Intervention\Image\Geometry\Circle;
+use Intervention\Image\Geometry\Point;
+use Intervention\Image\Tests\BaseTestCase;
+
+final class CircleTest extends BaseTestCase
+{
+    public function testConstructor(): void
+    {
+        $circle = new Circle(100, new Point(1, 2));
+        $this->assertInstanceOf(Circle::class, $circle);
+        $this->assertEquals(100, $circle->diameter());
+        $this->assertInstanceOf(Point::class, $circle->pivot());
+    }
+
+    public function testSetGetDiameter(): void
+    {
+        $circle = new Circle(100, new Point(1, 2));
+        $this->assertEquals(100, $circle->diameter());
+        $result = $circle->setDiameter(200);
+        $this->assertInstanceOf(Circle::class, $result);
+        $this->assertEquals(200, $result->diameter());
+        $this->assertEquals(200, $circle->diameter());
+    }
+
+    public function testSetGetRadius(): void
+    {
+        $circle = new Circle(100, new Point(1, 2));
+        $this->assertEquals(50, $circle->radius());
+        $result = $circle->setRadius(200);
+        $this->assertInstanceOf(Circle::class, $result);
+        $this->assertEquals(400, $result->diameter());
+        $this->assertEquals(400, $circle->diameter());
+        $this->assertEquals(200, $result->radius());
+        $this->assertEquals(200, $circle->radius());
+    }
+}