Update workflows to use .NET 8.0 also. (#1681)

@@ -125,9 +125,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: |
-            6.0.x
-            7.0.x
+          dotnet-version: 8.0.x
 
       - name: Install Python dependencies
         shell: bash

@@ -75,10 +75,10 @@ jobs:
         run: |
           df -h
 
-      - name: Setup .NET 6.0
+      - name: Setup .NET 8.0
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: 6.0.x
+          dotnet-version: 8.0.x
 
       - name: Check dotnet
         run: dotnet --info

@@ -115,8 +115,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: |
-            6.0.x
+          dotnet-version: 8.0.x
 
       - name: Check dotnet
         run: dotnet --info