changelog: drop redundant new attribute

Changelog

@@ -7,13 +7,13 @@ version 10:
 - reference-counting for AVFrame and AVPacket data
 - avconv now fails when input options are used for output file
   or vice versa
-- new avconv options -filter_script and -filter_complex_script, which allow a
+- avconv options -filter_script and -filter_complex_script, which allow a
   filtergraph description to be read from a file
 - uniform options syntax across all filters
-- new interlace filter
+- interlace filter
 - JPEG 2000 decoder
-- new asetpts filter (same as setpts, but for audio)
-- new trim and atrim filters
+- asetpts filter (same as setpts, but for audio)
+- trim and atrim filters
 - avconv -t and -ss (output-only) options are now sample-accurate when
   transcoding audio
 - Matroska muxer can now put the index at the beginning of the file.