Support SourceMod builds from GitHub releases (1.13.7305+)

[Copilot]

Since alliedmodders/sourcemod#2422, new SourceMod builds are published as GitHub releases instead of smdrop, making builds >1.13.7304 inaccessible to this action.

Changes

• Dual-source version resolution: getVersions() now fetches from both smdrop and the GitHub releases API concurrently via Promise.allSettled(). Either source can fail independently — a warning is emitted and resolution continues with the remaining source. Only throws if both fail.
• GithubVersion class: Extends Version with a direct browser_download_url override for toEndpoint(), bypassing the smdrop URL construction.
• Paginated GitHub releases scraper: getGithubVersions() pages through api.github.com/repos/alliedmodders/sourcemod/releases, parsing tags in 1.13.0.7316 format and matching platform-specific assets (sourcemod-1.13.0-git7316-linux.tar.gz). GitHub releases take precedence over smdrop for any overlapping build numbers.
• github-token input: Optional action input (falls back to GITHUB_TOKEN env var) for authenticated GitHub API requests to avoid rate limiting.

Usage

- uses: rumblefrog/setup-sp@master
  with:
    version: '1.13.x'
    github-token: ${{ secrets.GITHUB_TOKEN }}