svt-av1: remove BSD-2 from licenses

Quoting from the README:

> Up to v0.8.7, SVT-AV1 is licensed under the BSD-2-clause license and
> the Alliance for Open Media Patent License 1.0. See LICENSE and
> PATENTS for details. Starting from v0.9, SVT-AV1 is licensed under
> the BSD-3-clause clear license and the Alliance for Open Media
> Patent License 1.0. See LICENSE and PATENTS for details.

pkgs/tools/video/svt-av1/default.nix

@@ -27,7 +27,6 @@ stdenv.mkDerivation rec {
     changelog = "https://gitlab.com/AOMediaCodec/SVT-AV1/-/blob/v${version}/CHANGELOG.md";
     license = with licenses; [
       aom
-      bsd2
       bsd3
     ];
     platforms = platforms.unix;