unused_capture_list false positive with explicit capturing of unowned self in Swift 5.3

[lordzsolt]

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

Describe the bug

Same issue as #3267 but with unowned instead of strong.

Complete output when running SwiftLint, including the stack trace and command used

$ swiftlint lint Example.swift --no-cache                   
Linting Swift files at paths Example.swift
Linting 'Example.swift' (1/1)
Example.swift:14:50: warning: Unused Capture List Violation: Unused reference self in a capture list should be removed. (unused_capture_list)
Done linting! Found 1 violation, 0 serious in 1 file.

Environment

• SwiftLint version (run swiftlint version to be sure)? 0.40.3

• Installation method used (Homebrew, CocoaPods, building from source, etc)? Cocoapods

• Paste your configuration file: none, unused_capture_list is enabled by default

• Are you using nested configurations? No

• Which Xcode version are you using (check xcodebuild -version)? Xcode 12.2 Beta

• Do you have a sample that shows the issue?

override func viewDidLoad() {
	super.viewDidLoad() {
		rx.onViewDidAppear.subscribe(onNext: { [unowned self] in 
			doSomething()
		}).disposed(by: disposeBag)
	}

	func doSomething() {
		print("Watch this")
	}
}