$series is using wrong column

[Semptic]

Seems like the audible library export output changed (I'm using audible-cli version 0.2.4). The extraction in

AAXtoMP3/AAXtoMP3

Lines 567 to 568 in e66c51d

	series_title=$(echo "${lib_entry}" | awk -F '\t' '{print $6}')
	series_sequence=$(echo "${lib_entry}" | awk -F '\t' '{print $7}')

uses column 6 and 7 but in my library.tsv those series infos are at column 7 and 8.

E.g.:

# head -n 1 library.tsv | awk -F '\t' '{print $6}'
narrators

# head -n 1 library.tsv | awk -F '\t' '{print $7}'
series_title