CI: Install ffmpeg using brew if running on arm64 macos

[rosenbjerg]

Migrate to macos-latest (arm64) runners from macos-13 (intel) due to deprecation of intel based macos runners

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.20%. Comparing base (1c4333e) to head (7e135a7).
⚠️ Report is 21 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #576   +/-   ##
=======================================
  Coverage   71.20%   71.20%           
=======================================
  Files         117      117           
  Lines        2973     2973           
  Branches      284      284           
=======================================
  Hits         2117     2117           
  Misses        751      751           
  Partials      105      105           

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[Copilot]

Pull Request Overview

This PR updates the CI workflow to better support ARM64 macOS by switching to a different FFmpeg setup action and adjusting the runner configuration. The PR also includes code style improvements by removing redundant public modifiers from interface method declarations.

• Updated macOS runner from macos-13 to macos-latest for ARM64 support
• Replaced FFmpeg setup action with AnimMouse/setup-ffmpeg for better cross-platform compatibility
• Removed redundant public modifiers from interface method declarations

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
.github/workflows/ci.yml	Updated CI workflow to use different FFmpeg setup actions and ARM64 macOS runner
FFMpegCore/FFMpeg/Arguments/VideoFiltersArgument.cs	Removed redundant public modifiers from interface properties
FFMpegCore/FFMpeg/Arguments/IDynamicArgument.cs	Removed redundant public modifier from interface method

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