The introduction of async/await in Swift 5.5 (https://github.com/apple/swift-evolution/blob/main/proposals/0296-async-await.md) promoted the "await" word to keyword. Therefore to use it in the context of function call, it must be wrapped in backticks, just as for the methods called with other language keywords.
I've made a PR that adds the backticks in the right place: #57
Change is compatible with previous Swift versions.