Aac-datasets

Added
- `freesound_no_clotho_v2` subset to WavCaps to avoid all bias with Clotho test and analysis subsets.

Fixed
- WavCaps download preparation (3).
- `safe_rmdir` function when sub-directories are deleted.

Changed
- Update typing for paths with python class `Path`.
- Refactor functional interface to load raw metadata for each dataset.
- Refactor class variables to init arguments.
- Faster AudioCaps download with `ThreadPoolExecutor`.

Added
- `AudioCaps.DOWNLOAD_AUDIO` class variable for compatibility with [audiocaps-download 1.0](https://github.com/MorenoLaQuatra/audiocaps-download).

Changed
- Set log level to WARNING if verbose<=0 in check.py and download.py scripts.
- Use `yt-dlp` instead of `youtube-dl` as backend to download AudioCaps audio files.. ([1](https://github.com/Labbeti/aac-datasets/issues/1))
- Update default download message for AudioCaps. ([1](https://github.com/Labbeti/aac-datasets/issues/1))
- Update error message when checksum is invalid for Clotho and MACS datasets. ([2](https://github.com/Labbeti/aac-datasets/issues/2))

Added
- First experimental implementation of **WavCaps** dataset.
- Subsets `dcase_t2a_audio` and `dcase_t2a_captions` from the DCASE Challenge task 6b, in Clotho dataset.
- Subset `train_v2` for AudioCaps dataset.
- Dataset cards as separate dataclasses for each dataset.
- Get and set global user paths for root, ffmpeg and ytdl.
- Base class for all datasets to simplify manipulation of loaded data.

Changed
- Rename `test` subset to `dcase_aac_test`, `analysis` subset to `dcase_aac_analysis` from the DCASE Challenge task 6a, in Clotho dataset.
- Function `get_install_info` now returns `package_path`.

Added
- Script check.py now check if the audio files exists.
- Option `VERIFY_FILES` for Clotho and MACS datasets to validate checksums.
- `CITATION` global constant for each dataset.

Changed
- Methods `at` and `getitem` now use correct typing when passing an integer, list, slice or None values.

Fixed
- Python minimal version in README and pyproject.toml.
- Transform applied in `getitem` method when argument is not an integer.
- Incompatibility with `torchaudio>=2.0`.
- Remove 'tags' from AudioCaps columns when with_tags=False.