dietpi-software: support dated BirdNET-Go nightly asset names

[Copilot]

BirdNET-Go nightly assets now include a date suffix (e.g. birdnet-go-linux-arm64-20260712.tar.gz), while DietPi only matched the old non-suffixed filename. This caused URL resolution for BirdNET-Go installs/updates to miss current nightly artifacts.

• Installer URL matching (dietpi/dietpi-software)

  • Relaxed BirdNET-Go release asset matching to accept both legacy and dated nightly tarball names.
  • Keeps backward compatibility with previously published nightly names.

• URL updater workflow (.github/workflows/update_urls.bash)

  • Updated BirdNET-Go aCHECK extraction regex to capture optional -YYYYMMDD suffix.
  • Updated aREGEX replacement matcher so automated URL refreshes continue to patch dietpi-software correctly.

• Release notes (CHANGELOG.txt)

  • Added a v10.6 bugfix entry documenting BirdNET-Go install failure caused by newly date-suffixed nightly archives.

# before
...-linux-$arch\.tar\.gz

# after
...-linux-$arch(?:-[0-9]{8})?\.tar\.gz