Suppress PHP warning when using date_default_timezone_get()

Thanks to @nem25 for reporting this

CHANGELOG.md

@@ -8,6 +8,7 @@ Released: -
 * [Changed] Improve documentation
 * [Changed] Replace `version_compare()` with `PHP_VERSION_ID` in
             `index.php.dist` (available since PHP 5.2.7)
+* [Fixed] Suppress PHP warning when using `date_default_timezone_get()`
 ```
 
 ### Version 1.0.0

lib/Pico.php

@@ -498,7 +498,7 @@ class Pico
             // explicitly set a default timezone to prevent a E_NOTICE
             // when no timezone is set; the `date_default_timezone_get()`
             // function always returns a timezone, at least UTC
-            $this->config['timezone'] = date_default_timezone_get();
+            $this->config['timezone'] = @date_default_timezone_get();
         }
         date_default_timezone_set($this->config['timezone']);
     }