Adjust ffmpeg version detection in admin panel (mastodon#31130)

Co-authored-by: Claire <[email protected]>

app/lib/admin/metrics/dimension/software_versions_dimension.rb

@@ -98,15 +98,16 @@ def imagemagick_version
   end
 
   def ffmpeg_version
-    version = `ffmpeg -version`.match(/ffmpeg version ([\d\.]+)/)[1]
+    version_output = Terrapin::CommandLine.new(Rails.configuration.x.ffprobe_binary, '-show_program_version -v 0 -of json').run
+    version = Oj.load(version_output, mode: :strict, symbol_keys: true).dig(:program_version, :version)
 
     {
       key: 'ffmpeg',
       human_key: 'FFmpeg',
       value: version,
       human_value: version,
     }
-  rescue Errno::ENOENT
+  rescue Terrapin::CommandNotFoundError, Terrapin::ExitStatusError, Oj::ParseError
     nil
   end