`swiftlint lint --fix --use-stdin` does not print fixed source

### New Issue Checklist - [x] I've Updated SwiftLint to the latest version. - [x] I've searched for [existing GitHub issues](https://github.com/realm/SwiftLint/issues). ### Bug Description With the example below, `cat file.swift | swiftlint lint --fix --use-stdin` prints the unfixed content again to STDOUT. I'm not sure if autocorrections were not applied at all or if only some are applied (but not vertical_whitespace). ```swift // Copyright func foo( ) { print( some ) } ``` ```bash $ cat file.swift | swiftlint lint --fix --use-stdin ``` Running `swiftlint lint --fix file.swift` actually corrects the file. ```bash $ swiftlint lint --fix ./file.swift Correcting Swift files at paths ./file.swift Correcting 'file.swift' (1/1) /home/jansorg/temp/swiftSimple/file.swift: Corrected vertical_whitespace 3 times Done correcting 1 file! ``` Fixed content if not using `--use-stdin`: ```swift // Copyright func foo( ) { print( some ) } ``` ### Environment * SwiftLint version 0.63.1 * Xcode version none (Linux) * Installation method used Arch package manager * Configuration file: none