tests: make dotnet test run for Argon.FSharp.Tests

[MangelMaxime]

Hello,

While taking a look at Argon.FSharp for suggesting an improvement I discovered that I was not able to run the dotnet test against Argon.FSharp.Tests.

➜  Argon.FSharp.Tests git:(main) ✗ dotnet test
Restore complete (0.7s)
  Argon net9.0 succeeded (0.1s) → /Users/mmangel/Workspaces/Github/SimonCropp/Argon/src/Argon/bin/Debug/net9.0/Argon.dll
  Argon.FSharp net9.0 succeeded (0.1s) → /Users/mmangel/Workspaces/Github/SimonCropp/Argon/src/Argon.FSharp/bin/Debug/net9.0/Argon.FSharp.dll
  Argon.Xml net9.0 succeeded (0.1s) → /Users/mmangel/Workspaces/Github/SimonCropp/Argon/src/Argon.Xml/bin/Debug/net9.0/Argon.Xml.dll
  Argon.NodaTime net9.0 succeeded (0.1s) → /Users/mmangel/Workspaces/Github/SimonCropp/Argon/src/Argon.NodaTime/bin/Debug/net9.0/Argon.NodaTime.dll
  Argon.DataSets net9.0 succeeded (0.1s) → /Users/mmangel/Workspaces/Github/SimonCropp/Argon/src/Argon.DataSets/bin/Debug/net9.0/Argon.DataSets.dll
  Argon.JsonPath net9.0 succeeded (0.1s) → /Users/mmangel/Workspaces/Github/SimonCropp/Argon/src/Argon.JsonPath/bin/Debug/net9.0/Argon.JsonPath.dll
  Argon.InterfaceCallbacks net9.0 succeeded (0.1s) → /Users/mmangel/Workspaces/Github/SimonCropp/Argon/src/Argon.InterfaceCallbacks/bin/Debug/net9.0/Argon.InterfaceCallbacks.dll
  ArgonTests net9.0 succeeded (0.2s) → /Users/mmangel/Workspaces/Github/SimonCropp/Argon/src/ArgonTests/bin/Debug/net9.0/ArgonTests.dll
  Argon.FSharp.Tests failed with 1 error(s) (0.5s)
    /Users/mmangel/Workspaces/Github/SimonCropp/Argon/src/Argon.FSharp.Tests/Program.fs(1,1): error FS0222: Files in libraries or multiple-file applications must begin with a namespace or module declaration. When using a module declaration at the start of a file the '=' sign is not allowed. If this is a top-level module, consider removing the = to resolve this error.

Because Argon.FSharp.Tests is not an executable we can simply remove Program.fs and then run dotnet test against the project.

[SimonCropp]

thanks