Don't filter libimage-exiftool-perl

[gm10]

A user on the forums was wondering why he couldn't install it via Software Manager, I think it warrants getting added to the exceptions, see its description, it has a stand-alone part:

Description: library and program to read and write meta information in multimedia files
Image::ExifTool is a Perl module with an included command-line application
called exiftool for reading and writing meta information in a wide variety of
files, [...]