Add support for slnx files (#36)

Author: sailro

README.md

@@ -17,7 +17,7 @@ dotnet tool install -g dotnet-delice
 You can then use it like so:
 
 ```
-dotnet delice [folder, sln, csproj, fsproj]
+dotnet delice [folder, sln, slnx, csproj, fsproj]
 ```
 
 ## Commands
@@ -68,6 +68,10 @@ License Expression: MIT
 - Ability to filter for only a particular license
 - Anything you'd like? Open an [issue](https://github.com/aaronpowell/dotnet-delice/issues) 😁
 
+# Slnx support
+
+XML-based solution file format (slnx) are supported, but you need at least a `.NET 9.0.201 SDK` which provides support for interacting with these files.
+
 # Undetermined Licenses
 
 At the end of 2018 the [`licenseUrl` field in the nuspec file was deprecated](https://github.com/NuGet/Announcements/issues/32) to be replaced with a richer license metadata field. You can read more about it in the [annuncement](https://github.com/NuGet/Announcements/issues/32), the [documentation](https://docs.microsoft.com/en-us/nuget/reference/nuspec?WT.mc_id=dotnet-0000-aapowell#license) and [Spec wiki](https://github.com/NuGet/Home/wiki/Packaging-License-within-the-nupkg).

src/DotNetDelice/App.fs

@@ -16,6 +16,7 @@ let (|Proj|_|) arg =
         String.Compare(str, arg, StringComparison.OrdinalIgnoreCase) = 0
 
     if c ".sln" then Some()
+    elif c ".slnx" then Some()
     elif c ".csproj" then Some()
     elif c ".fsproj" then Some()
     else None
@@ -28,7 +29,7 @@ let findProject path =
         | Proj -> Path.GetFullPath path
         | _ -> failwith "Path is not a valid project or solution path"
     | (_, true) ->
-        match Directory.GetFiles(path, "*.sln") with
+        match Directory.GetFiles(path, "*.sln") |> Array.append <| Directory.GetFiles(path, "*.slnx") with
         | [| sln |] -> Path.GetFullPath sln
         | [||] ->
             match
@@ -87,7 +88,7 @@ let getLicensesForTool checkGitHub token checkLicenseContent (projectSpec: Packa
 type Cli() =
 
     [<Argument(0,
-               Description = "The path to a .sln, .csproj or .fsproj file, or to a directory containing a .NET Core solution/project. If none is specified, the current directory will be used.")>]
+               Description = "The path to a .sln, .slnx, .csproj or .fsproj file, or to a directory containing a .NET Core solution/project. If none is specified, the current directory will be used.")>]
     member val Path = "" with get, set
 
     [<Option(Description = "Output result as JSON")>]