add support for laravel 9.x

composer.json

@@ -10,7 +10,7 @@
         }
     ],
     "require": {
-        "laravel/framework": "~5.2|^6.0|^7.0|^8.0"
+        "laravel/framework": "~5.2|^6.0|^7.0|^8.0|^9.0"
     },
     "require-dev": {
         "orchestra/testbench": "~3.0|~4.0|~5.0|~6.0",

phpunit.xml

@@ -1,22 +1,13 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="vendor/autoload.php"
-         backupGlobals="false"
-         backupStaticAttributes="false"
-         colors="true"
-         verbose="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         processIsolation="false"
-         stopOnFailure="false">
-    <testsuites>
-        <testsuite name="Laravel Settings Test Suite">
-            <directory>tests</directory>
-        </testsuite>
-    </testsuites>
-    <filter>
-        <whitelist>
-            <directory suffix=".php">src/</directory>
-        </whitelist>
-    </filter>
-</phpunit>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" bootstrap="vendor/autoload.php" backupGlobals="false" backupStaticAttributes="false" colors="true" verbose="true" convertErrorsToExceptions="true" convertNoticesToExceptions="true" convertWarningsToExceptions="true" processIsolation="false" stopOnFailure="false" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+  <coverage>
+    <include>
+      <directory suffix=".php">src/</directory>
+    </include>
+  </coverage>
+  <testsuites>
+    <testsuite name="Laravel Settings Test Suite">
+      <directory>tests</directory>
+    </testsuite>
+  </testsuites>
+</phpunit>