Small fix to work around older NUnit version in internal build
Small fix to work around older NUnit version in internal build

alfonsogarciacaro/FSharp.Compiler.Service,sergey-tihon/FSharp.Compiler.Service,eloraiby/fsharp,dsyme/fsharp,In2TheWild/fsharp,syeerzy/visualfsharp,rneatherway/FSharp.Compiler.Service,dsyme/fsharp,alfonsogarciacaro/FSharp.Compiler.Service,dsyme/fsharp,matthid/FSharp.Compiler.Service,vasily-kirichenko/FSharp.Compiler.Service,dsyme/FSharp.Compiler.Service,cloudRoutine/FSharp.Compiler.Service,fsharp/fsharp,Heather/fsharp,rojepp/FSharp.Compiler.Service,Jand42/FSharp.Compiler.Service,forki/FSharp.Compiler.Service,rojepp/FSharp.Compiler.Service,ncave/FSharp.Compiler.Service,dsyme/FSharp.Compiler.Service,vasily-kirichenko/FSharp.Compiler.Service,matthid/FSharp.Compiler.Service,syeerzy/visualfsharp,wk-j/fsharp,ncave/FSharp.Compiler.Service,brettfo/visualfsharp,fsharp/fsharp,dsyme/fsharp,alfonsogarciacaro/FSharp.Compiler.Service,0x53A/FSharp.Compiler.Service,syeerzy/visualfsharp,syeerzy/visualfsharp,brettfo/visualfsharp,BillHally/FSharp.Compiler.Service,mafiya69/fsharp,Jand42/FSharp.Compiler.Service,rojepp/FSharp.Compiler.Service,yever/FSharp.Compiler.Service,sergey-tihon/FSharp.Compiler.Service,forki/FSharp.Compiler.Service,0x53A/FSharp.Compiler.Service,cloudRoutine/FSharp.Compiler.Service,BillHally/FSharp.Compiler.Service,sergey-tihon/FSharp.Compiler.Service,rneatherway/FSharp.Compiler.Service,matthid/FSharp.Compiler.Service,cloudRoutine/FSharp.Compiler.Service,dsyme/FSharp.Compiler.Service,brettfo/visualfsharp,Heather/fsharp,wk-j/fsharp,forki/FSharp.Compiler.Service,brettfo/visualfsharp,syeerzy/visualfsharp,yever/FSharp.Compiler.Service,dsyme/fsharp,brettfo/visualfsharp,Jand42/FSharp.Compiler.Service,0x53A/FSharp.Compiler.Service,eloraiby/fsharp,dsyme/fsharp,fsharp/fsharp,vasily-kirichenko/FSharp.Compiler.Service,mafiya69/fsharp,syeerzy/visualfsharp,dsyme/fsharp,In2TheWild/fsharp,brettfo/visualfsharp,ncave/FSharp.Compiler.Service