Update Tests.fs

[FoggyFinder]

fix problem with decimal separator

[FoggyFinder]

It's just a workaround. Perhaps this solution would be more appropriate:

let culture = System.Threading.Thread.CurrentThread.CurrentCulture

[<SetUp>]
let setup () =
    System.Threading.Thread.CurrentThread.CurrentCulture <- System.Globalization.CultureInfo.InvariantCulture

[<TearDown>]
let teardown () =
    System.Threading.Thread.CurrentThread.CurrentCulture <- culture