fate: add test for the unsharp video filter.

tests/lavfi-regression.sh

@@ -45,6 +45,7 @@ do_lavfi "setdar"             "setdar=16/9"
 do_lavfi "setsar"             "setsar=16/11"
 do_lavfi "thumbnail"          "thumbnail=10"
 do_lavfi "transpose"          "transpose"
+do_lavfi "unsharp"            "unsharp=10:10:-1.5:10:10:-1.5"
 do_lavfi "vflip"              "vflip"
 do_lavfi "vflip_crop"         "vflip,crop=iw-100:ih-100:100:100"
 do_lavfi "vflip_vflip"        "vflip,vflip"

tests/ref/lavfi/unsharp

+unsharp             73e38eb0e598230dcbbb1802c35e8dcd