Fix fatal error in PHP 8.1 (#8108)

PHP Fatal error: Declaration of LORIS\Log\ErrorLogLogger::log($level, $message, array $context = []) must be compatible with Psr\Log\LoggerTrait::log($level, Stringable|string $message, array $context = []): void in /var/www/Loris/src/Log/ErrorLogLogger.php on line 65

src/Log/ErrorLogLogger.php

@@ -62,7 +62,7 @@ private function interpolate(string $message, array $context = array()) : string
      *
      * @throws \Psr\Log\InvalidArgumentException
      */
-    public function log($level, $message, array $context = array())
+    public function log($level, $message, array $context = array()): void
     {
         // LogLevel consts are strings, not integers, so we need to
         // be explicit about which are used instead of doing a < or >