Fix typo in GD stub

Author: nikic

ext/gd/gd.stub.php

@@ -236,6 +236,6 @@ function imageaffinematrixconcat(array $m1, array $m2): array|false {}
 
 function imagegetinterpolation(GdImage $im): int {}
 
-function imagesetinterpolation(GdImage $im, int $method = IMG_BILENEAR_FIXED): bool {}
+function imagesetinterpolation(GdImage $im, int $method = IMG_BILINEAR_FIXED): bool {}
 
 function imageresolution(GdImage $im, int $res_x = UNKNOWN, int $res_y = UNKNOWN): array|bool {}