upgrade phpunit

.gitignore

@@ -2,3 +2,4 @@ composer.lock
 vendor/
 coverage/
 .DS_Store
+.phpunit.result.cache

composer.json

@@ -14,7 +14,7 @@
     "php": ">=5.5"
   },
   "require-dev": {
-    "phpunit/phpunit": "^4.8.13",
+    "phpunit/phpunit": "^8.5",
     "predis/predis": "1.1.*"
   },
   "autoload": {

tests/integration/CacheTest.php

@@ -1,5 +1,5 @@
 <?php
-class CacheTest extends PHPUnit_Framework_TestCase {
+class CacheTest extends \PHPUnit\Framework\TestCase {
 
   public function testCreateFromConfig() {
     p3k\Cache::redis('tcp://127.0.0.1:6379');

tests/unit/DateTest.php

@@ -1,5 +1,5 @@
 <?php
-class DateTest extends PHPUnit_Framework_TestCase {
+class DateTest extends \PHPUnit\Framework\TestCase {
 
   public function testFormatLocalPositiveOffset() {
     $local = p3k\date\format_local('c', '2017-05-01T13:30:00+0000', 7200);

tests/unit/URLTest.php

@@ -1,5 +1,5 @@
 <?php
-class URLTest extends PHPUnit_Framework_TestCase {
+class URLTest extends \PHPUnit\Framework\TestCase {
 
   public function testDisplayURL() {
     $url = p3k\url\display_url('http://example.com');

tests/unit/UtilsTest.php

@@ -1,5 +1,5 @@
 <?php
-class UtilsTest extends PHPUnit_Framework_TestCase {
+class UtilsTest extends \PHPUnit\Framework\TestCase {
 
   public function testRandomString() {
     $str1 = p3k\random_string(20);