Migrate CI to GitHub Actions

[adam-rocska]

Summary

• Replace the Travis CI setup with a GitHub Actions workflow.
• Preserve the old meaningful Linux Swift release coverage with Docker-based jobs for Swift 4.0.3, 4.1.3, 4.2.4, 5.0.3, and 5.1.
• Add a current macOS smoke job so the package still has macOS build/test coverage after leaving Travis.
• Remove the Travis configuration and update README/generated docs badges to point at GitHub Actions.

Why

Travis CI is stale for this repository and depends on old Travis-specific matrix behavior plus Package-Builder. Keeping that configuration around makes the repository look noisier than it is and points contributors at a CI system that is no longer the maintainable path.

The new workflow keeps this first pass conservative. The Linux jobs continue to exercise the historical Swift release line through the same official Swift Docker images used by the old setup. The old development snapshot lane and dead Xcode image lanes are intentionally not recreated; those are no longer stable CI targets and should be handled separately as part of an explicit support-policy pass.

Cost and operations

This workflow uses standard GitHub-hosted runners for a public repository. The Linux jobs run on the standard Ubuntu runner and execute the official Swift Docker images. The macOS job uses the standard GitHub-hosted macOS runner. No larger runners, paid external CI service, persistent caches, or uploaded artifacts are used.

Validation

• Parsed .github/workflows/ci.yml as YAML locally.
• Verified there are no remaining Travis, Package-Builder, TRAVIS_, or old build-status references in the repository.
• Ran git diff --check successfully.
• Ran swift test locally on macOS; both KituraCache tests passed.
• GitHub Actions passed on this PR for Swift 4.0.3, 4.1.3, 4.2.4, 5.0.3, 5.1, and the macOS default Swift smoke job.

Notes

This is a CI migration, not a broader platform modernization. It restores a useful baseline signal without trying to recreate obsolete Travis/Xcode infrastructure.

[adam-rocska]

@dannys42 , @LowAmmo or @mbarnach : we happy?

I'd upgrade the swift versions & whatnot afterwards. This repo I think is a good candidate form my modernization rampage. Safe position in the dependency graph, not too popular, and its "recent" history is mostly cricket chirp and tumbleweed.

[Copilot]

Pull request overview

This PR migrates the repository’s CI from Travis CI to GitHub Actions, keeping historical Linux Swift coverage via official Swift Docker images while adding a minimal macOS smoke build/test job.

Changes:

• Added a GitHub Actions workflow with a Linux matrix (Swift 4.0.3, 4.1.3, 4.2.4, 5.0.3, 5.1) running builds/tests inside Docker, plus a macOS build/test job.
• Removed the legacy Travis CI configuration.
• Updated README and generated docs badges to point at the new GitHub Actions workflow.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
README.md	Replaces the Travis badge with a GitHub Actions CI badge.
docs/index.html	Updates the generated docs badge to GitHub Actions.
docs/docsets/KituraCache.docset/Contents/Resources/Documents/index.html	Updates the docset’s embedded badge to GitHub Actions.
.travis.yml	Removes Travis CI configuration.
.github/workflows/ci.yml	Adds the new GitHub Actions workflow (Linux Docker matrix + macOS smoke job).

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