Bonsai debian9 filter definition is too broad

[nixwiz]

The filters debian 9 are too broad, either remove or add debian platform_family and version to filter

- platform: "debian9"
  arch: "amd64"
  asset_filename: "#{repo}_#{version}_debian9_linux_amd64.tar.gz"
  sha_filename: "#{repo}_#{version}_sha512-checksums.txt"
  filter:
  -  "entity.system.os == 'linux'"
  -  "entity.system.arch == 'amd64'"