Fix bug in Alfred 4 using getenv() (#15)

* Replace $_ENV with getenv();

* Update README

* Update README.md

* support older PHP versions

`getenv('alfred_theme_subtext') ?? '0'` would be ideal, but let's KISS

Co-authored-by: Till Krüss <tillkruss@users.noreply.github.com>

README.md

@@ -1,6 +1,6 @@
 # Laravel Docs Workflow for Alfred
 
-An ultra-fast Laravel docs search workflow for [Alfred 3](https://www.alfredapp.com).
+An ultra-fast Laravel docs search workflow for [Alfred 3+](https://www.alfredapp.com).
 
 ![Screenshot](screenshot.png)
 

laravel.php

@@ -15,14 +15,18 @@
     $branch = $matches[1];
     $query = $matches[2];
 } else {
-    $branch = $_ENV['branch'];
+    $branch = getenv('branch');
 }
 
 if ($branch === 'latest') {
     $branch = null;
 }
 
-$subtext = empty($_ENV['alfred_theme_subtext']) ? '0' : $_ENV['alfred_theme_subtext'];
+$subtext = getenv('alfred_theme_subtext');
+
+if (empty($subtext)) {
+    $subtext = '0';
+}
 
 $workflow = new Workflow;
 $parsedown = new Parsedown;