Fix kokoro v3

[alphanota]

Fixes: #nnn
Related: Relevant tracking issues, for context
Merge before/after: Dependent or prerequisite PRs

Description

User facing changes (remove if N/A)

Follow-up Work (remove if N/A)

[code-review-assist]

Hi team,

I'm currently reviewing this pull request and will provide feedback shortly. In the meantime, here's a summary for you and other reviewers to quickly get up to speed:

This pull request, "Fix kokoro v3", aims to update the Kokoro build system (likely version 3). The description lacks specifics, so this summary is based solely on the code changes. I'll update this summary once I've fully reviewed the PR.

Changes:

• .github/workflows/compile-mac.yaml: A new workflow file has been added for cross-compilation of Skaffold on MacOS. This workflow is triggered on push and pull request events and includes steps for checking out code, setting up Go, caching build artifacts, and building Skaffold binaries for various platforms (linux-amd64, darwin-amd64, windows-amd64.exe, linux-arm64, darwin-arm64).
• Makefile: A minor change on line 77. The -extldflags argument in the ldflags variable has been modified to remove unnecessary escaping of the % character. Additionally, on line 80, single quotes have been added around $(ldflags) in the go build command. This likely addresses an issue with shell expansion or argument parsing.

Potential Impact: This change directly impacts the build process of Skaffold, particularly cross-compilation on macOS. It might improve build reliability or address compatibility issues with Kokoro v3.

I'll provide a more detailed review shortly, but this should give everyone a good starting point.

---

And now, a little haiku to brighten your day:

Code flows like a stream,
Fixes merge, a gentle hum,
Builds now run so smooth.

[code-review-assist]

This PR adds a macOS cross-compilation workflow which is a valuable addition. The implementation looks good overall, but I have a few minor suggestions for improvement.