feat: adds --version option

tests/Unit/Plugins/Version.php

@@ -0,0 +1,20 @@
+<?php
+
+use Pest\Plugins\Version;
+use Symfony\Component\Console\Output\BufferedOutput;
+
+it('outputs the version when --version is used', function () {
+    $output = new BufferedOutput();
+    $plugin = new Version($output);
+
+    $plugin->handleArguments(['foo', '--version']);
+    assertEquals("Pest    0.2.2\n", $output->fetch());
+});
+
+it('do not outputs version when --version is not used', function () {
+    $output = new BufferedOutput();
+    $plugin = new Version($output);
+
+    $plugin->handleArguments(['foo', 'bar']);
+    assertEquals('', $output->fetch());
+});