beets: remove usage of ? null

pkgs/tools/audio/beets/builtin-plugins.nix

@@ -1,13 +1,13 @@
 { stdenv
-, aacgain ? null
+, aacgain
-, essentia-extractor ? null
+, essentia-extractor
-, ffmpeg ? null
+, ffmpeg
-, flac ? null
+, flac
-, imagemagick ? null
+, imagemagick
-, keyfinder-cli ? null
+, keyfinder-cli
 , lib
-, mp3gain ? null
+, mp3gain
-, mp3val ? null
+, mp3val
 , python3Packages
 , ...
 }: {

pkgs/tools/audio/beets/common.nix

@@ -10,14 +10,14 @@
 , writeScript
 
   # plugin deps
-, aacgain ? null
+, aacgain
-, essentia-extractor ? null
+, essentia-extractor
-, ffmpeg ? null
+, ffmpeg
-, flac ? null
+, flac
-, imagemagick ? null
+, imagemagick
-, keyfinder-cli ? null
+, keyfinder-cli
-, mp3gain ? null
+, mp3gain
-, mp3val ? null
+, mp3val
 
 , src
 , version