Consolidate .NET setup calls.

Author: tillig

.github/workflows/build.yml

@@ -11,18 +11,13 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
-      - name: Setup .NET 6
+      - name: Setup .NET
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: 6.0.x
-      - name: Setup .NET 7
-        uses: actions/setup-dotnet@v4
-        with:
-          dotnet-version: 7.0.x
-      - name: Setup .NET 8
-        uses: actions/setup-dotnet@v4
-        with:
-          dotnet-version: 8.0.x
+          dotnet-version: |
+            6.0.x
+            7.0.x
+            8.0.x
       - name: Build and test
         run: dotnet msbuild ./default.proj
       - name: Upload coverage