fate: gif: change checksum to bgr8 from rgb8 as thats what gets selected now

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

tests/ref/lavf/gif

@@ -1,7 +1,7 @@
 e6089fd4ef3b9df44090ab3650bdd810 *./tests/data/lavf/lavf.gif
 2906401 ./tests/data/lavf/lavf.gif
 ./tests/data/lavf/lavf.gif CRC=0xe5605ff6
-fc4792ac40319344dc7027668a403fc3 *./tests/data/images/gif/02.gif
+022dc66b5068404e88c618ce79d9eb5f *./tests/data/images/gif/02.gif
 ./tests/data/images/gif/%02d.gif CRC=0x032e0034
 81538 ./tests/data/images/gif/02.gif
 759522b3025fcf8ed6aae582a18c5a14 *./tests/data/images/gif/02.gif