Fix lints

Author: horgh

autoload.php

@@ -35,7 +35,7 @@ function mmdb_autoload($class): void
         $path = str_replace('\\', '/', $path);
 
         // and finally, add the PHP file extension to the result.
-        $path = $path . '.php';
+        $path .= '.php';
 
         // $path should now contain the path to a PHP file defining $class
         if (file_exists($path)) {

src/MaxMind/Db/Reader/Decoder.php

@@ -265,7 +265,7 @@ private function decodePointer(int $ctrlByte, int $offset): array
         $pointerSize = (($ctrlByte >> 3) & 0x3) + 1;
 
         $buffer = Util::read($this->fileStream, $offset, $pointerSize);
-        $offset = $offset + $pointerSize;
+        $offset += $pointerSize;
 
         switch ($pointerSize) {
             case 1: