chore(deps): downgrade to phpunit 9

Because:
We need to support PHP 7.4 until we fully upgrade every app

composer.json

@@ -17,7 +17,7 @@
         "slim/slim": "^3.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^10.0"
+        "phpunit/phpunit": "^9.6"
     },
     "autoload": {
         "psr-4": {

phpunit.xml.dist

@@ -1,23 +1,29 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.6/phpunit.xsd"
          bootstrap="vendor/autoload.php"
-         cacheDirectory=".phpunit.cache"
+         cacheResultFile=".phpunit.cache/test-results"
+         colors="true"
          executionOrder="depends,defects"
-         requireCoverageMetadata="true"
-         beStrictAboutCoverageMetadata="true"
+         forceCoversAnnotation="true"
+         beStrictAboutCoversAnnotation="true"
          beStrictAboutOutputDuringTests="true"
+         beStrictAboutTodoAnnotatedTests="true"
+         convertDeprecationsToExceptions="true"
          failOnRisky="true"
-         failOnWarning="true">
+         failOnWarning="true"
+         verbose="true"
+    >
     <testsuites>
-        <testsuite name="Slim Test Suite">
+        <testsuite name="default">
             <directory>tests</directory>
         </testsuite>
     </testsuites>
 
-    <source restrictDeprecations="true" restrictNotices="true" restrictWarnings="true">
+    <coverage cacheDirectory=".phpunit.cache/code-coverage"
+              processUncoveredFiles="true">
         <include>
-            <directory>src</directory>
+            <directory suffix=".php">src</directory>
         </include>
-    </source>
+    </coverage>
 </phpunit>

tests/SmartyTest.php

@@ -25,6 +25,9 @@ public function setUp(): void
         $this->view->addSlimPlugins($mockRouter, 'base_url_test');
     }
 
+    /**
+     * @covers \Slim\Views\Smarty::fetch
+     */
     public function testFetch()
     {
         $output = $this->view->fetch('hello.tpl', [
@@ -34,6 +37,9 @@ public function testFetch()
         $this->assertEquals("<p>Hello, my name is Matheus.</p>\n", $output);
     }
 
+    /**
+     * @covers \Slim\Views\Smarty::render
+     */
     public function testRender()
     {
         $mockBody = $this->getMockBuilder('Psr\Http\Message\StreamInterface')
@@ -59,13 +65,19 @@ public function testRender()
         $this->assertInstanceOf('Psr\Http\Message\ResponseInterface', $response);
     }
 
+    /**
+     * @covers \Slim\Views\Smarty::fetch
+     */
     public function testPlugin()
     {
         $output = $this->view->fetch('plugin.tpl');
 
         $this->assertEquals("<p>Plugin return: base_url_test.</p>\n", $output);
     }
 
+    /**
+     * @covers \Slim\Views\Smarty::getSmarty
+     */
     public function testPluginDirs()
     {
         $this->assertGreaterThanOrEqual(2, count($this->view->getSmarty()->getPluginsDir()));