Ensure we set up .NET 6 and .NET 8

Author: jskeet

.github/workflows/pull-request.yaml

@@ -15,9 +15,11 @@ jobs:
         submodules: true
 
     - name: Setup .NET SDK
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v4
       with:
-        dotnet-version: '6.0.x'
+        dotnet-version: |
+          6.0.x
+          8.0.x
         
     - name: Build and test
       run: |

.github/workflows/push.yaml

@@ -18,9 +18,11 @@ jobs:
         submodules: true
 
     - name: Setup .NET SDK
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v4
       with:
-        dotnet-version: '6.0.x'
+        dotnet-version: |
+          6.0.x
+          8.0.x
         
     - name: Build and test
       run: |