[swift] give lane_context return_type of hash_with_strings

[joshdholtz]

Fixes #12303

Wut

• No return type so Swift returned nothing when laneContext was called 😊

class Fastfile: LaneFile {
	func testLane() {

		let changelog = changelogFromGitCommits(commitsCount: 1)
		puts(message: "changelog: \(changelog)")

		let dict = laneContext()
		puts(message: "dict: \(dict["FL_CHANGELOG"])")
	}
}

But now we can do something like this ^

[taquitos]

🎷:goat:

[fastlane-bot]

Hey @joshdholtz 👋

Thank you for your contribution to fastlane and congrats on getting this pull request merged 🎉
The code change now lives in the master branch, however it wasn't released to RubyGems yet.
We usually ship about once a week, and your PR will be included in the next one.

Please let us know if this change requires an immediate release by adding a comment here 👍
We'll notify you once we shipped a new release with your changes 🚀

[fastlane-bot]

Congratulations! 🎉 This was released as part of fastlane 2.92.0 🚀