Flacmirror

Fixed
- Resample audio files if their samplerate is not supported by fdkaac.

Added
- MP3 support (using ffmpeg with libmp3lame as an encoder)
- AAC support (using fdkaac as an encoder)
- New example section in readme

Changed
- Fix readme showing wrong python version
- Switch to using hatch for project management
- Release on pypi

Added
- Make flacmirror work with the python -m flag

Changed
- Add CI, nothing changed for flactools itself

Fixed
- Set the correct minimum python version to 3.7 instead of 3.6

Changed
- Change output file extension from .ogg to .opus for opus encoded files
Some media players do not seem to like like the .ogg extension for opus audio files
and the .opus extension is also [recommended](https://datatracker.ietf.org/doc/html/rfc7845#section-9).
- To fix (recursively rename files from ogg to opus) already synced directories you can use the
following command under linux:
bash
find . -name '*.ogg' -exec rename .ogg .opus {} +