manual PATH scanner instead of command

command is not always available in shell_exec()
see chrome-php#613 for details

src/AutoDiscover.php

@@ -39,8 +39,24 @@ public function guessChromeBinaryPath(): string
                 return '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome';
             case 'Windows':
                 return self::getFromRegistry() ?? '%ProgramFiles(x86)%\Google\Chrome\Application\chrome.exe';
-            default:
-                return \rtrim(\explode("\n", (string) self::shellExec('command -v google-chrome chromium-browser chrome chromium'), 2)[0]) ?: 'chrome';
+            default: {
+                    $valid_names = array(
+                        'google-chrome',
+                        'chromium-browser',
+                        'chrome',
+                        'chromium',
+                    );
+                    foreach (\explode(\PATH_SEPARATOR, \getenv('PATH')) as $dir) {
+                        foreach ($valid_names as $name) {
+                            $file = $dir . \DIRECTORY_SEPARATOR . $name;
+                            if (\is_file($file) && \is_executable($file)) {
+                                return $file;
+                            }
+                        }
+                    }
+                    return 'chrome'; // ... very unlikely to actually work, but this retains the original behavior..
+                    throw new \RuntimeException('Could not find chrome binary'); // this makes more sense tbh
+            }
         }
     }