Minor improvements

Author: antonkomarev

README.md

@@ -2,16 +2,16 @@
 
 PHP Client for [Gauge Exporter](https://github.com/belka-tech/gauge-exporter). 
 
-
 ## Usage example
+
 ```php
 <?php
 
 use BelkaTech\GaugeExporterClient\GaugeExporterClient;
 use BelkaTech\GaugeExporterClient\MetricBag;
 use GuzzleHttp\Client;
 
-require_once "vendor/autoload.php";
+require_once 'vendor/autoload.php';
 
 $bag = new MetricBag('metric-name');
 $bag->increment(['a' => 'b'], 100);

tests/GaugeExporterClientTest.php

@@ -13,7 +13,7 @@
 use PHPUnit\Framework\TestCase;
 use Psr\Http\Message\RequestInterface;
 
-class GaugeExporterClientTest extends TestCase
+final class GaugeExporterClientTest extends TestCase
 {
     public function testGaugeExporterClientHostTrailingSlashTrimmed(): void
     {

tests/MetricBagTest.php

@@ -9,7 +9,7 @@
 use InvalidArgumentException;
 use PHPUnit\Framework\TestCase;
 
-class MetricBagTest extends TestCase
+final class MetricBagTest extends TestCase
 {
     public function testCannotCreateMetricWithEmptyName(): void
     {