contrib: taglib: bump to 2.1
- Support for Shorten (SHN) files.
- Compile time configuration of supported formats: WITH_APE, WITH_ASF, ...
- Compile time configuration of data and temporary directories for unit tests:
- TESTS_DIR and TESTS_TMPDIR.
- C bindings: Added taglib_file_new_wchar() and taglib_file_new_type_wchar().
- Preserve unicode encoding when downgrading to ID3v2.3.
- Do not store FLAC metadata blocks which are too large.
- Fix segfaults with String and ByteVector nullptr arguments.
Release note: https://github.com/taglib/taglib/releases/tag/v2.1