PHP8.3 compatibility #2 (#20)

* PHP8.3 compatibility

Turns out PHP<8.3's proc_open does not really care if the requested working_dir does not exist, while PHP>=8.3's proc_open bails if it does not exist.

And due to a typo in the code, the dir never existed.

And due to insufficient error checking, the error was not really detected.

Took fking 4 hours to track down, and the fix is 1 byte. divinity76#1

Should probably complain to the php-src bugtracker, i am guessing the proc_open behavior change was unintentional

* StyleCI

tests/Test/ServerTestHelper.php

@@ -111,9 +111,11 @@ public function setUp(): void
                 2 => ['file', $directory.'/server.err.log', 'a+'],
             ],
             $this->pipes,
-            __DIR__.'../'
+            __DIR__.'/../'
         );
-
+        if (false === $this->process) {
+            throw new \RuntimeException('proc_open failed: '.\var_export(\error_get_last(), true));
+        }
         \sleep(3);
     }