fix: ffmpeg terminated prematurely

[ffrejaa]

Summary

See issue #2205

When streaming audio from a pipe the ffmpeg process would be terminated immediately
if there was no data left to read from the pipe. This lead to some of the audio being cut off before being fully processed by ffmpeg

This PR closes the ffmpeg process stdin instead and lets ffmpeg close itself gracefully

Information

• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed).
• This PR is not a code change (e.g. documentation, README, typehinting,
  examples, ...).

Checklist

• I have searched the open pull requests for duplicates.
• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• If type: ignore comments were used, a comment is also left explaining why.
• I have updated the changelog to include these changes.