force correct c# to be installed

Author: CamJN

.github/workflows/dotnet.yml

@@ -17,7 +17,14 @@ jobs:
   build:
 
     runs-on: macos-latest
-
+    name: .NET ${{ matrix.dotnet }}
+    strategy:
+      matrix:
+        dotnet:
+          - 8.0.x # EOL: 2026-11-10
+          - 7.0.x # EOL: 2024-05-14
+          - 6.0.x # EOL: 2024-11-12
+# version support doc: https://dotnet.microsoft.com/en-us/platform/support/policy/dotnet-core
     steps:
     - uses: actions/checkout@v3
       with:
@@ -30,11 +37,13 @@ jobs:
     - uses: actions/checkout@v3
       with:
         path: getargv.cs
-    # - name: Setup .NET
-    #   uses: actions/setup-dotnet@v3
-    #   with:
-    #     dotnet-version: 7.0.x
-    # version support doc: https://dotnet.microsoft.com/en-us/platform/support/policy/dotnet-core
+    - name: Setup .NET
+      uses: actions/setup-dotnet@v4
+      with:
+        dotnet-version: ${{ matrix.dotnet }}
+    - name: Create temporary global.json
+      run: echo '{"sdk":{"version": "${{ steps.stepid.outputs.dotnet-version }}"}}' > ./global.json
+      working-directory: getargv.cs
     - name: Restore dependencies
       run: dotnet restore
       working-directory: getargv.cs