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/Traits/HasBorderTest.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Unit\Geometry\Traits;
+
+use Intervention\Image\Geometry\Traits\HasBorder;
+use Intervention\Image\Tests\BaseTestCase;
+
+final class HasBorderTest extends BaseTestCase
+{
+    public function getTestObject(): object
+    {
+        return new class () {
+            use HasBorder;
+        };
+    }
+
+    public function testSetBorder(): void
+    {
+        $object = $this->getTestObject();
+        $this->assertNull($object->borderColor());
+        $this->assertEquals(0, $object->borderSize());
+        $this->assertFalse($object->hasBorder());
+        $object->setBorder('fff', 10);
+        $this->assertEquals('fff', $object->borderColor());
+        $this->assertEquals(10, $object->borderSize());
+        $this->assertTrue($object->hasBorder());
+    }
+
+    public function testSetBorderSize(): void
+    {
+        $object = $this->getTestObject();
+        $this->assertEquals(0, $object->borderSize());
+        $object->setBorderSize(10);
+        $this->assertEquals(10, $object->borderSize());
+    }
+
+    public function testSetBorderColor(): void
+    {
+        $object = $this->getTestObject();
+        $this->assertNull($object->borderColor());
+        $object->setBorderColor('fff');
+        $this->assertEquals('fff', $object->borderColor());
+        $this->assertFalse($object->hasBorder());
+    }
+
+    public function testHasBorder(): void
+    {
+        $object = $this->getTestObject();
+        $this->assertFalse($object->hasBorder());
+        $object->setBorderColor('fff');
+        $this->assertFalse($object->hasBorder());
+        $object->setBorderSize(1);
+        $this->assertTrue($object->hasBorder());
+    }
+}