This file was renamed in #173993 from settings.gradle to settings.gradle.kts, but the string format wasn't fixed; Kotlin strings need to use ", not '.

I was curious how this was working, so I tried deleting it locally from a freshly created test plugin (along with the settings.gradle that had been created; that was on stable so may have already been fixed), and the example app still compiled. Maybe this file is unused? Or only used in some edge case (non-flutter-tool) scenarios where gradle commands are being run directly against the plugin project?

We should at least fix the string delimiters, and maybe also figure out if we should just delete the whole file.