Fix PHPUnit configuration deprecation warning

- Migrate PHPUnit configuration to use latest schema
- Remove deprecated XML structure
- Add cacheDirectory attribute and source block
- All tests now pass without deprecation warnings

Author: farhadzand

phpunit.xml

@@ -1,37 +1,30 @@
 <?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="vendor/autoload.php"
-         colors="true"
-         testdox="true">
-    <testsuites>
-        <testsuite name="Unit">
-            <directory suffix="Test.php">./tests/Unit</directory>
-        </testsuite>
-        <testsuite name="Feature">
-            <directory suffix="Test.php">./tests/Feature</directory>
-        </testsuite>
-    </testsuites>
-
-    <coverage includeUncoveredFiles="true" processUncoveredFiles="true">
-        <include>
-            <directory suffix=".php">./src</directory>
-        </include>
-        <exclude>
-            <directory suffix=".php">./src/Storage</directory>
-            <directory suffix=".php">./src/Exceptions</directory>
-        </exclude>
-    </coverage>
-
-    <php>
-        <env name="APP_ENV" value="testing"/>
-        <env name="PROMETHEUS_ENABLED" value="true"/>
-        <env name="PROMETHEUS_STORAGE_DRIVER" value="memory"/>
-        <ini name="error_reporting" value="E_ALL &amp; ~E_DEPRECATED"/>
-        <ini name="memory_limit" value="512M"/>
-    </php>
-
-    <logging>
-        <junit outputFile="build/logs/junit.xml"/>
-    </logging>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd" bootstrap="vendor/autoload.php" colors="true" testdox="true" cacheDirectory=".phpunit.cache">
+  <testsuites>
+    <testsuite name="Unit">
+      <directory suffix="Test.php">./tests/Unit</directory>
+    </testsuite>
+    <testsuite name="Feature">
+      <directory suffix="Test.php">./tests/Feature</directory>
+    </testsuite>
+  </testsuites>
+  <php>
+    <env name="APP_ENV" value="testing"/>
+    <env name="PROMETHEUS_ENABLED" value="true"/>
+    <env name="PROMETHEUS_STORAGE_DRIVER" value="memory"/>
+    <ini name="error_reporting" value="E_ALL &amp; ~E_DEPRECATED"/>
+    <ini name="memory_limit" value="512M"/>
+  </php>
+  <logging>
+    <junit outputFile="build/logs/junit.xml"/>
+  </logging>
+  <source>
+    <include>
+      <directory suffix=".php">./src</directory>
+    </include>
+    <exclude>
+      <directory suffix=".php">./src/Storage</directory>
+      <directory suffix=".php">./src/Exceptions</directory>
+    </exclude>
+  </source>
 </phpunit>