tests/api/api-codec-param-test: Do not directly access caps_internal

The caps_internal field has moved without major bump and direct
access causes crashes, found when testing 3.1
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

tests/api/api-codec-param-test.c

@@ -50,7 +50,7 @@ static int try_decode_video_frame(AVCodecContext *codec_ctx, AVPacket *pkt, int
         goto end;
     }
 
-    if (!decode && codec_ctx->codec->caps_internal & FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM) {
+    if (!decode && avpriv_codec_get_cap_skip_frame_fill_param(codec_ctx->codec)) {
         codec_ctx->skip_frame = AVDISCARD_ALL;
     }