Switch to .NET 5.0; use NuGet OVRSharp

Author: tjhorner

.github/workflows/release.yml

@@ -13,7 +13,7 @@ jobs:
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 3.1.402
+        dotnet-version: "5.0.x"
     - name: Install dependencies
       run: dotnet restore
     - name: Build
@@ -35,7 +35,7 @@ jobs:
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 3.1.402
+        dotnet-version: "5.0.x"
     - name: Install dependencies
       run: dotnet restore
     - name: Build

README.md

@@ -10,7 +10,7 @@ This is a very, very, _very_ simple OpenVR overlay that literally just puts an a
 
 [Here](https://github.com/tjhorner/WhereIsForward/releases)
 
-You might need the [.NET Core Desktop Runtime](https://download.visualstudio.microsoft.com/download/pr/1b3a8899-127a-4465-a3c2-7ce5e4feb07b/1e153ad470768baa40ed3f57e6e7a9d8/windowsdesktop-runtime-5.0.0-win-x64.exe) if you don't already have it. (Or you can download the self-contained version instead, which includes the .NET Core runtime.)
+You might need the [.NET Desktop Runtime](https://download.visualstudio.microsoft.com/download/pr/1b3a8899-127a-4465-a3c2-7ce5e4feb07b/1e153ad470768baa40ed3f57e6e7a9d8/windowsdesktop-runtime-5.0.0-win-x64.exe) if you don't already have it. (Or you can download the self-contained version instead, which includes the .NET runtime.)
 
 ### Why?