Upgrade to PHPUnit 11 and modernize configuration

Changes:
- Upgrade PHPUnit from ^9.5 to ^11.5
- Add rector/rector ^2.2 for code quality
- Update phpunit.xml.dist for PHPUnit 10+ compatibility:
  - Move include/exclude to <source> element
  - Move cacheDirectory to <phpunit> root element
  - Remove deprecated processUncoveredFiles attribute

PHPUnit 11 requires PHP 8.2+ which matches project requirements.
This also fixes php-parser compatibility with readonly class syntax
in --prefer-lowest CI runs.

Author: koriym

composer.json

@@ -20,7 +20,8 @@
         "ext-redis": "*",
         "ext-memcached": "*",
         "bamarni/composer-bin-plugin": "^1.4",
-        "phpunit/phpunit": "^9.5.28"
+        "phpunit/phpunit": "^11.5.43",
+        "rector/rector": "^2.2"
     },
     "autoload": {
         "psr-4": {

phpunit.xml.dist

@@ -1,12 +1,17 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd"
-  bootstrap="tests/bootstrap.php">
-  <coverage cacheDirectory=".phpunit.cache/code-coverage"
-    processUncoveredFiles="true">
+  bootstrap="tests/bootstrap.php"
+  cacheDirectory=".phpunit.cache">
+  <source>
     <include>
       <directory suffix=".php">src</directory>
     </include>
+    <exclude>
+      <directory suffix=".php">src-deprecated</directory>
+    </exclude>
+  </source>
+  <coverage>
   </coverage>
   <testsuites>
     <testsuite name="Ray.PsrCacheModule test suite">