Use `--depth 1` for cloning

[Cyberbeni]

We don't need to clone the whole repository, just the last commit

Action-setup-swift/src/main.ts

Line 28 in 8b4f6ec

await exec.exec('git', ['clone', 'https://github.com/kylef/swiftenv.git', swiftenvDirectory]);

[YOCKOW]

@Cyberbeni
That's a good point.
I'll fix it in the near future.