FSharpLint not working

I've installed FSharpLint by doing ```dotnet tool install -g dotnet-fsharplint```, and tried one of their examples on the [FSharpLint website](https://fsprojects.github.io/FSharpLint/):
```
type ExampleInterface =
abstract member print : unit -> unit

[]
let main argv =
let x = List.fold (fun x y -> x + y) 0 [1;2;3]
printfn "%d" x
0
```

**Expected behaviour**
I expect that Nvim should give me virtual text diagnostic warnings that are like this:
however I am not seeing any warnings:

**Environment (please complete the following information):**
- OS: Archlinux
- Vim / Neovim version: NVIM v0.7.0-dev+1241-g08d9d74fd
- dotnet SDK version: 6.0.102
- mono / .Net Framework version: 6.0.102