Fix release workflow build failures

[DePasqualeOrg]

The weekly release workflow has been failing since late October 2025. There were two independent problems:

1. Release script stuck on outdated milestones

getNextRelease() always targets latestRelease + 1, so after M141 it kept trying to build M142 every week. M142's buildtools were incompatible with the CI runner, so it failed repeatedly while Chromium stable advanced to M144.

The script now queries the Chromium Dashboard fetch_milestones API for the current stable milestone and skips ahead to it. If the API call fails, the script exits with an error.

2. Xcode SDK incompatibility

WebRTC milestone branches ship with frozen Chromium buildtools that only support the Xcode/SDK version current at the time of the branch cut. As GitHub Actions runner images update, newer Xcode versions introduce SDK framework splits (e.g. DarwinFoundation, UIUtilities) that break the build.

Both workflows now pin Xcode 16.1 (the version expected by current buildtools — see build/mac_toolchain.py in the WebRTC source). This needs to be updated when future milestones require a newer Xcode. The manual build workflow also uploads the build output as a zip to preserve macOS framework symlinks.

Other minor changes:

• Use GITHUB_REPOSITORY env var for all GitHub API calls instead of hardcoding stasel/WebRTC. This makes the script work when run from forks.
• Replaced automated PR body, which contained a typo and a grammatical error, with a descriptive message.
• Changed schedule from weekly to daily. The script exits early when no new release is available.
• Fixed version regex in release script sed commands to match any X.Y.Z version instead of only X.0.0. Patch releases (e.g. 144.0.1) would break the URL update in Package.swift.

Testing

The workflow ran successfully and produced releases of the latest versions on DePasqualeOrg/WebRTC. The x.0.1 patch versions have been patched for the missing header issue mentioned below, so they work on iOS and macOS.

Note: Milestones M141–M144 have a separate issue where framework headers aren't copied into the bundle (webrtc:450130875), which causes build failures in Xcode. CL 424441 fixed this for iOS but not for macOS — the macOS framework is still missing headers as of M145. The upstream fix adds create_bracket_include_headers as a dependency for mac_framework_bundle but doesn't copy the generated headers into the bundle's Versions/A/Headers/ directory.

[stasel]

Hi @DePasqualeOrg
Huge thanks for this. I will take a look at it soon