[PHPStan] Rename and modernize phpunit.xml.dist

Author: lkck24

phpunit.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation = "./vendor/phpunit/phpunit/phpunit.xsd"
+    cacheResultFile="./data/phpunit.result.cache"
+    colors                        = "true">
+  <testsuites>
+    <testsuite name="Unit">
+      <directory suffix="Test.php">./tests/</directory>
+    </testsuite>
+  </testsuites>
+</phpunit>